He's not horrible as antag, but I think as a raider, meaning verses PVE, he is way too strong. He marginalizes the threat of bosses completely. It's good I guess if you just want to complete boss objectives quickly and you have no antagonist, but it kind of makes it so you don't actually play the mission. And for antag this sucks because he deletes the boss before the antag can even do anything, and if Schnieder is antag he deletes the old man without even having to kill a single raider.
Schneider is NOT fragile, he is of the Hades Division faction and so has the most health, along with them, in the game of 140. He can also get the same cards as them, such as black belt and cycle of violence, so CQC isn't his weak point.