I'll disagree that it was some sort of "smokescreen" or ruse to cover for his knowledge about the assassination - I think Oswald acted on his own volition - but I do agree that Castro was not exactly saddened over JFK's death. The radical publications that Oswald read were filled with stories quoting Castro's condemnation of JFK and the White House's policies towards Cuba.
And remember that just about one year before this - in October of 1962 - Castro communicated with Khrushchev during the missile crisis and begged him to launch his (Khrushchev's) nuclear missiles at the US. Here is Khrushchev's account about receiving the message:
"He [Castro] proposed that to prevent destruction of our missile installations, we should immediately strike first, dealing a [preemptive] thermonuclear blow to the United States.
"When this message was read aloud to us, we sat there in silence, looking at one another for a long time. It became clear at that point that Fidel absolutely did not understand our intentions. He assumed....that we wanted to use Cuban territory as a base right up next to the United States to install our missiles and to strike a blow at the United States with those missiles. It's true of course that that was a very good forward position from which to strike a sudden surprise blow with missiles. But we
absolutely never wanted to make such a strike." -Memoirs of Nikita Khrushchev, Volume 3. pg. 341
I don't think that in a year that Castro's hatred towards the "imperialists" completely changed to the point that he was depressed over JFK's death.
Castro was like many politicians, and sometimes said things that just weren’t true. Here’s a continuation of Jean Daniel’s article:
Now it was nearly 2 o’clock and we got up from the table and settled ourselves in front of a radio. Commandant Vallero, his physician, aide-de-camp, and intimate friend, was easily able to get the broadcasts from the NBC network in Miami. As the news came in, Vallero would translate it for Fidel: Kennedy wounded in the head; pursuit of the assassin; murder of a policeman; finally the fatal announcement: President Kennedy is dead. Then Fidel stood up and said to me: “Everything is changed. Everything is going to change. The United States occupies such a position in world affairs that the death of a President of that country affects millions of people in every corner of the globe. The cold war, relations with Russia, Latin America, Cuba, the Negro question… all will have to be rethought. I’ll tell you one thing: at least Kennedy was an enemy to whom we had become accustomed. This is a serious matter, an extremely serious matter.”
After the quarter-hour of silence observed by all the American radio stations, we once more tuned in on Miami; the silence had only been broken by a re-broadcasting of the American national anthem. Strange indeed was the impression made, on hearing this hymn ring out in the house of Fidel Castro, in the midst of a circle of worried faces. “Now,” Fidel said, “they will have to find the assassin quickly, but very quickly, otherwise, you watch and see, I know them, they will try to put the blame on us for this thing. But tell me, how many Presidents have been assassinated? Four? This is most disturbing! In Cuba, only one has been assassinated. You know, when we were hiding out in the Sierra there were some (not in my group, in another) who wanted to kill Batista. They thought they could do away with a regime by decapitating it. I have always been violently opposed to such methods. First of all from the viewpoint of political self-interest, because so far as Cuba is concerned, if Batista had been killed he would have been replaced by some military figure who would have tried to make the revolutionists pay for the martyrdom of the dictator. But I was also opposed to it on personal grounds; assassination is repellent to me.”
The real Fidel Castro:
Quote from “Guerrilla Prince” by Georgie Anne Geyer:
“Fidel made his debut in Cuban politics by organizing the demonstration against Grau and his supposedly innocent increase in the bus fares. ...
...At this point, Fidel suddenly whispered to his coconspirators, "I have the formula to take power and once and for all get rid of this old son-of-a-As I was walking a' alane, I heard twa corbies makin' a mane. The tane untae the tither did say, Whaur sail we gang and dine the day, O. Whaur sail we gang and dine the day? It's in ahint yon auld fail dyke I wot there lies a new slain knight; And naebody kens that he lies there But his hawk and his hound, and his lady fair, O. But his hawk and his hound, and his lady fair. His hound is to the hunting gane His hawk to fetch the wild-fowl hame, His lady ta'en anither mate, So we may mak' our dinner swate, O. So we may mak' our dinner swate. Ye'll sit on his white hause-bane, And I'll pike oot his bonny blue e'en Wi' ae lock o' his gowden hair We'll theek oor nest when it grows bare, O. We'll theek oor nest when it grows bare. There's mony a ane for him maks mane But nane sail ken whaur he is gane O'er his white banes when they are bare The wind sail blaw for evermair, O. The wind sail blaw for evermair.'." His comrades were stupefied as he explained, "Now, when the old guy returns, let's pick him up, the four of us, and throw him off the balcony. Once the president is dead, we'll proclaim the triumph of the student revolution and speak to the people from the radio." "Vamos, guajiro, tú estás 'chiflado'" ("Listen, redneck, you're nuts"), Chino Esquivel told him. And when Fidel insisted on his astounding plan, Enrique Ovares finally squelched it by saying, "We came here to ask for a lowering of the fares on the buses, not to commit an assassination." It is important to remember that Grau, for all his faults, was not a dictator but one of Cuba's first democratically elected leaders.”
