No they don't!
Whatever gave you that idea?
If that were the case, everybody would think infamous evil people shouldn't be jailed. After all, what did Peter Sutcliffe do to me?
(just using him as a reference point as he is a famous - or rather infamous-person NOT to be controversial).
You meet a child abusing piece of scum and you judge him on how he treats you? Don't be f*ing daft.
I'm sorry but most people do NOT say, 'Aye I know he did x, y, z' but he's OK to me. '
Not unless they are indeed thick as the proverbial.
Your second point about greater good is not relevant here.
I don't tend to vote for the greater good, anyway.
You are unable to grasp what I believe to be the very basic concept that this is not about saying every man who stays with his family is good.
It is about saying that those that abandon their family guilt - free are bad.
If you consider it to be a vetting process, and left family is test number one then they are eliminated at the first hurdle.
There may be other tests they fail later but you can get rid of them from the start.
The last bit about denigrating mn-ers is irrelevant.