Yeah, I would be upset too. I'm even more upset because people make these viruses to begin with and this poor chap got chapped. Basically, his machine had a big infection and Avast stopped it and wouldn't let him reinfect the machine again because he wanted his infected files put back where they were before he ran a virus scan. Something like, "I think I will install Avast and run a scan." And then, "Oh, Avast found hundreds of infected files and won't put them back where they were before." And then, "Hey you guys screwed up my machine and I want you to fix it now!" I'm sure we are not getting the whole story here.
So, I believe the whole thing was another hoax by someone that likes something other than Avast and wants to stir up a negative record on the forums. Avast seems to be making it's competitor's and it's competitor's fans upset to the point that they feel it is necessary to bring bogus melodrama to the forums.