It feels like Sirius is putting people through emotional trauma in the guise of teaching.
Yes. And? Quite often the only way to teach people a thing is to have them experience the results of their actions first.
Sirius is extremely protective of his "family", but he is
also a very strict taskmaster, who is not afraid to visit bodily harm to his pupils to make a point.
Or let bodily harm visit them if they ignore what he's trying to teach. He's a Master in Emotional Damage...
And the World, either ours or theirs... isn't a Nice Fluffy Place that insta-rewards Acts of Defiant Heroïsm.
Quite the contrary, as the ...kids... are finding out, despite Sirius' warnings and
quite explicit instructions.
They're not in immediate mortal danger, so Sirius isn't acting
right now.
He's allowing them to have a little lesson in Life. Particularly the "Don't Storm In Blindly And Expect To Get Away With It." one.
Harsh? Maybe... But this world is, in many ways, quite harsh and dangerous.