Why not?
Like a lot of CTers, Alan, try not to overthink the "conspiracy." It didn't take ridiculous theories like squirreling away the body mid-drive to Love, throwing the body down into the cargo hold, squireling it away at Andrews in full view of live TV cameras and the family, and altering it...for what reason?
It didn't take faking the Z film and then ("Oh, by the way") altering the Nix film, and then the Muchmore film, and all the rest. It didn't take having an assassination HQ down in the basement of Ruby's nightclub (an actual "theory" by someone posted on the Ed Forum).
And, for the love of god, it didn't take finding an Oswald clone off the streets of Hungary 13 years before 11/22 - and a clone of Oswald's Mom no less - to groom him and live in the real Oswald's shadow as a young boy until 11/22.
Narrow it down to the bare essentials and it makes a whole lot more sense than all the rest of the mumbo jumbo. Read Bill Simpich's State Secret - there, you'll find that Oswald was not just some innocent dock worker like the WC wants him to be. As Simpich says, Oswald was a "spy in his own mind" but was little more than a low-level intel guy who could be easily led around, probably with promises of something more down the road. He could easily be moved into the TSDB building when it was decided that the shooting was going to take place there.
Meanwhile, if they knew then he was going to be the patsy, then the wheels turned to get it ready - faked backyard photos (Oswald himself said they were faked), getting him to hand out pro Commie literature in NO and all the rest. They even got him to say things along those lines on TV in NO. Watch that film clip - it's not hard to see he's play-acting his role.
On 11/22 they probably told him to stand by the phone for an important phone call. Did he know this was all going to go down? It's hard to say but they knew he could be relied on to do what he was told. It makes absolutely no sense for him to be up on those steps during the actual assassination - it would have destroyed the entire charade of "Crazy Lee shooting the president."
Was he supposed to be gunned down at the TSBD? Probably not because 15 minutes after the shooting, a description of his *original* marked description from his false defection (read State Secret) was announced on the radio. Meanwhile, he casually takes his slow ride to Oak Cliff, all the while JDT is gunned down, marking him even more as a madman.
The key to the plot is his "I'm a patsy" statement. He obviously broke character and blurted that out. Think about it for a minute. My Dad was also an "order filler" and "dock worker" for most of his life. But I can guarantee you that he, and many others did not know what that word meant. Oswald did and he was no dummy - his wheels had obviously started spinning at this point when he said that - "OMG I see what's happening now." He had a lot of time to think about what had been going on before was murdered on Sunday.
Of course the WC wanted him to be like Tim McVeigh years later - a genuine angry "lone nut" who defiantly blew up the Fed building. Which leads me to the idea that Oswald was not quite as innocent as we think. IMO I think he knew *something* was going to go down on Elm Street - how much he knew was probably kept from him and we'll never know. But because LHO was not stupid - he was after all, trained at the intel base in Japan and prepped for his fake defection to Russia - he couldn't possibly have been kept 100% in the dark about 11/22.
So you see, Alan, you DO have to tie everything together in the pre and post assassination planning in order to make sense of it all. You can't cherry pick just to try to explain something that makes no sense - in this case being it's just *gotta be Oswald up on the steps there*.