Not sure about the Castro stuff.
Castro’s intelligence agency had reportedly infiltrated the CIA at that point in time with double agent(s). (Of course they were assisted by the Soviets.) I searched four books on Castro that I have in the Kindle format, but found no reference to the name Morales. Of course names are often changed for espionage purposes.
Many Cuban exiles supported Castro before he went full communist. He wouldn't be the first to switch from supporting Castro to opposing him.
Morales has been implicated in anti-Cuba terror attacks and he confessed to involvement in many attacks on Cuba. Hard to believe he would be connected to violent attacks on Cuba if he were a double-agent.
When Morales’s anti-Castro compatriots bombed a Polish ship and other communist targets in 1968, his fingerprints were found at one of the bombing scenes. The FBI received testimony that the explosives came from the CIA. Morales then became a witness for U.S. prosecutors. He wore a wire for the FBI while meeting with other Cuban suspects in the case. In a 1972 memo, the chief of the Agency’s Western Hemisphere division said the FBI considered Morales “honest and objective” as an informant.
So he was violent and likely a contract killer but also a US intelligence asset.
Apparently Morales made a lot of claims about his activities. It’s hard to believe that he was involved with all of them. The Oswald “connection” might just be one of the claims that will never be confirmed. And it is possible that his son just made it up for the purposes of attention getting and the money from the TV production that he is supposedly pursuing.
Morales' son seems pretty credible and his relationships with the FBI and CIA have been confirmed.
That doesn't mean Morales told his son the truth of course but it's at least plausible that he had some knowledge of the JFK assassination plot.