The most steam can do is investigate the program more but when making an anti cheat system the anticheat group works with the company that made the game.
The company that made the game will profile info that basically says them. while gaming, these memory values should be within these ranges, if they are not then the user is cheating. It is quite simple and is effective.
False positives usually happens if a user has an infection designed to steal info from games (such as account info), or has a kill tracker or other random program that hooks into the game to provide stuff like chats, music or other random stuff.
While mistakes can be made. It doesn't change the fact that more work needs to be done to ban cheaters, and unfortunately, due to the ever trickier ways people are cheating, it is getting more difficult to make a proper anticheat and thus more false positives may happen.