Well I strongly disagree with that decision and I think it's really disappointing to say the least, also because you could make a 1002 build which would only be applied for users which has the 8.3 tweak applied, it would be fairly easy to check, since all we are talking about is a reg key.
If it were fairly easy don't you think they would have considered it.
Assuming it were possible and easy to do what you propose, what about those millions who haven't applied the 8.3 tweak, effectively their systems wouldn't be updated and would remain as 4.7.1001 and those that did would be on 4.7.1002. There is only one current version of avast on the web site, there is only one current version available for download.
So the millions of users would appear to be running an out of date version.
What happens when a later program update comes out the checks you suggest would need to be done in perpetuity.