Well, that’s certainly one way to interpret it. Another way is that the point of prison is to separate someone from society, not to put them in physical harm. If an accountant embezzles from his employer, he should do time, but maybe surrounded by other accountants and not armed robbers.
I’m not talking about just Holmes here, but about prisons in general. It’s not supposed to be fun, but neither is it meant to support a collective revenge fantasy.
Elizabeth seems the sort of person most capable of executing a plan whereby she pulls off a prison break through enlisting the aid of a bunch of other prisoners who're promised freedom themselves, but in her plan are actually there as decoys to be killed. It seems analogous to stuff she's already happily done. She is potentially a risk even to other prisoners if she carries on as she has done. I don't buy that she's not a risk to others.