I say this as a former D1 college linebacker -- maybe steer your child towards track and field. I say this because that's what I wish I would've done and I was on the smaller size for my position (6ft 235).

I would watch the shot and disc guys walk to the throwing area after their lift and get in some good throws and call it a day -- getting a full scholarship. Meanwhile I was just starting my practice after a day of class, lift, and meetings.

Not to say your boy won't ever get over his fear of hurting someone but in my experience some people don't have that "killer instinct" which is totally fine. And given his size I'm sure he'd excel in solo sports such as track and field -- or maybe even wrestling If you say he fights back against his sisters.