Just read how the judge handled it. He made one mistake and it was a big one. Flynn stopped being a foreign agent before becoming NSA. But his team can't complain about it. Another judge could be much harsher.
Flynn was clearly guilty of serious crimes and considering the position of trust he took on, he had to say he couldn't take the role he was offered in the administration.
If they jailed people for hypocrisy, he should have a spell in jail over the 'Lock her up' comments. As things stand, the judge has essentially said he must continue providing support to Mueller until March. Good for the judge.
It sounds like Flynn needs to feel regret in a more obvious fashion.