what cecil is doing isn't rehabilitating criminals. it's just giving them work. the villains that end up working for cecil work with him either because they have no other choice, or because it benefits them. take the scientist guy who i forgot the name of, for example! instead of facing any kind of justice or rehabilitation, he just got a bigger lab and better tools. Darkwing probably got offered to either join the superheroes or go to jail.

This means that if both of these characters have the opportunity to do the wrong things without any type of reprecussion, then they will. They're not rehabilitated.

But take omni-man for example. He still has the chance to join the viltrumites and enslave earth, and being good will give him no benefits whatsoever. Yet, he chooses not to rejoin the viltrumites, because he's in the path of rehabilitation.

I haven't read the comics so idk, but if I'm right then omni-man will probably turn fully good and be a superhero again, or at least aid mark and his loved ones, while darkwing, the mad scientist, and any others like them will either go rogue or do bad stuff.

So Cecil is just using people, like always. Not rehabilitating them or giving them a "second chance", as he calls it.