Tim,
I think your theory is partly correct. However, this is what I think is more likely:
1. After the completed film was rated PG in November 1987, the studio decided to re-shoot at least part of the ending to make it more intense, in the hopes of getting a new rating of PG-13.
2. Planning for this re-shoot was going on between December 1987 and January 1988, with new SFX makeups being worked on (Kane's demise)
3. The re-shoot was probably scheduled for early February, but then Heather died February 1st.
4. After putting things on hold for a while, MGM decided to go ahead with the re-shoot (which took place the week of March 14, 1988), but this time they made some more changes by redoing the entire ending. They removed the frozen Carol Anne (likely for the reason Tim named above), and also left Scott out on purpose (Kipley Wentz has said no one ever asked him to be in the re-shoot, and he only learned there had been a re-shoot of the ending at the movie's premiere). "Scott" was likely left out because the studio felt that audiences might be confused over which was the "real" Scott (it was probably decided to make the Scott who comes up out of the pool be the real one, even though that still didn't make sense).
5. Also, there was a Writer's Guild strike going on, which began March 7, 1988. That meant that members of the Writer's Guild (Gary Sherman?) were not allowed to write anything while the strike was going on. However, the pages of the re-shot ending had a date of "Revised March 14, 1988" stamped on each page. Were WGA guild rules broken? Maybe. And perhaps that's (one) of the reasons why Gary still doesn't want to talk about it.
This post has been edited by dfurtney: 15 July 2009 - 08:29 AM