I don't want to go their but it'd be like having a gun as a kid. You're not allowed to use it, even if you've received training, but you could actually literally kill someone for real. Laws exist for a reason.
But you are allowed to use whatever you can get your hands on when someone is literally trying to kill you.

On the other hand, a rather good point by Spacewolf, it could be Eraser is just thinking ahead, or trying to make 100 % certain noone is holding back in any way.

Else, im behind the general consensus on Bakugou giving an explosive finger to any recuitment attemt that dont start with a massive knock to the head.