There are several related issues. Perhaps the one that you've brought up is more "obvious" than others, but what about someone in a tournament, where after 3 months they just "leave chess.com" and lose on time in all their remaining tournament games. It's not really fair to people who, as you say, "play more quickly", but perhaps this is one of the drawbacks to playing quickly. I think that this is not something which should be managed at the chess.com level, but rather that people who play quickly always assume some risk that other "as slow as legally possible, plus maybe some vacation time" players may end up with some bonus points as a result of their strategy.
Make sense?
When a cheater is deleted in a Tournament, I believe all his games should be deleted/defaulted and not just those games that are still running.
For example, if he has already won a against someone that plays more quickly, it unfairly punishes this victim (of cheating).
No big deal as Tourneys are just for fun .... just saying ....