Any answer can be wrong. This is what downvotes are for. The bigger concern is users who blindly vote and/or accept without checking the answer.
I'm no legal expert, but anyone should be able to rewrite the relevant information and cite the site(ha!). If this is done in a manner that makes the answer bad, that is what downvotes are for.
Games are updated on a regular basis. Answer rot is a valid concern, but "Google answers" are not the only source. My answer to a Terraria question was rendered incorrect by a recent patch. I play Terraria (ask John and Tristan) and wrote that answer from experience. By the time this had changed, I had completely forgotten that I answered that question. It wasn't until someone pointed out to me that the answer was outdated that I did anything about it. I saw that there were already other correct answers, so I deleted my answer.
Therefore, (correct) "Google answers" are not a problem. They fall victim to the same pitfalls that any source can. If anything, it is the way inexperienced (or sometimes experienced) users react to answers that is the problem.