The conspirators never anticipated that Lee would emerge alive from the TSBD. The script called for him to be shot and killed by an "alert cop" in the TSBD....
After the murder when LBJ learned that there were Russians and nuclear missiles in Cuba, and they didn't dare attack Cuba they had to "erase" Oswald's trip to Mexico city....and in fact they confused the issue by presenting photos of a man that obviously was NOT Lee Oswald at the Russian Embassy in Mexico city. By introducing this "evidence" they had suckers believing that Lee had NOT gone to Mexico City.
And yet the Warren Commission, who has been accused of lying, omitting vital evidence and completely ignoring witness statements entirely in order to come to the conclusion the government allegedly wanted it to, clearly stated that Oswald did go to Mexico City.
Without any conclusive evidence surely it would have been just as easy to for the WC to say that there was no evidence Oswald even went there and thus not raise the issue in the first place?
Its a nice theory and would make an entertaining movie starring Matt Damon, but as far as real life goes it's about as realistic as Moses parting the Red Sea