The thing is that kids memories can do crazy things. Children re-interpret, mis-interpret and inaccurately remember things. I remember thinking that when Luke shoots the stormtrooper on the chasm and he goes "oooh" and falls off the ledge that it was Han going "Luke! Nooo" because Luke accidentally shot him in disguise. In fact, TFN has a 50+ page thread about stuff like that, i think called "Things is Star Wars that you misunderstood as a Child" or something similar to that.
The fact that Foster admits he made it up is enough to totally discredit all these claims. Are we to believe that Foster invented something out of his own mind in order to add dramatic tension something that wasn't in the original version of the film but then was completely coincidentally found in an obscure TV version to be exactly the way Foster wrote it? Foster is saying he made it up, so for Lucas to film something, delete it and then add it in only for a once-in-a-lifetime TV broadcast and have it coincidentally be exactly the same as the way Foster invented it from his mind is too much of a coincidence to ignore.
Furthermore, the wildly different accounts of this scene indicate that its just childhood memories. Some say that Leia kissed Luke to inspire him after missing, some say that he just threw it before, some say it was a rare 1977 print, some say it was an obscure 80's TV broadcast. This goes hand in hand with people who claim "i remember seeing footage of Leia spitting on Vader," "I remember seeing the Biggs footage," "I remember Luke missing the rope," "I remember Luke accidentally shooting the controls,"--and in ever single one of thse, every single one from every single claim, the excuse is always "oh, but i haven't seen the tape that it was on for about two decades now--if only i still had it!" Gee, what a surprise.