'rough means' as in baseballs to train shields? Not really a bad guy.
'rough means' as in thralldom? Still a bad guy.
I still haven't worked out the thralldom part, but Yeah, baseballs aren't so bad. Harry survived and thrived AND learned the lesson.
Leah has a point in her training of Molly.
I imagine that Justin knew he had a short time to get these starborn trained.
Remember that he also used baseball as a reward for Harry lighting his fire.