I'm curious to know if IA has ways of detecting whether archived pages were deleted. If rewriting history has big implications, doing so for "the internet" would similarly be big.
Even a full deletion in one datacentre shouldn't erase an entire chunk like that.
If people have been in there for years altering data do they have enough backups to fully detect it?
Do they have mechanisms to verify existing data with backups? Are they even bothering? It would be nice to know - until then I think the IA is interesting, but not trustworthy.