As well as trivializing male rape it also obscures female experiences of rape that happen in prison-a lot.
The "fuck em, their criminals" attitude really amounts to an endorsement or rape under narrowly defined circumstances. If you prefer to passively let rapes happen when their prevention could be enforced by the state then you are signalling that you are in favor of it.
If that happens you are creating a part of our society where this type of torture is allowed, and some people living in that part of society will be released into the rest of society. Aside from just not wanting them to be raped because they are, you know, people-it's good to be mindful of that fact.