Howdy, Just noticed this as well. I've used systemrequirementlabs many times in the past and have found them to be rather safe. I find this to be a fp and hope avast reviews their mistake and corrects it, if not can you please at least explain why it was block?
From my knowledge the program they have you run only checks your PC's specs such as what graphics card you have, RAM, hard drive, and such needed to run a game. The website is very well helpful about what games you can or can not probably run on your computer.