I don't know about anybody else, but I never seem to make contact with ships at all. I actually thought there must have been an option hidden somewhere in the 'Create Game' screen where you could turn off ship collision, because I seem to pass right through everyone. I don't see how anyone could purposely be that aggresive.

Adding to that, even if it is possible, I still don't think it should be frowned apon.

Just look at racing against Elite A.I. with weapons off, the amount of ramming going on in there is amazing. You're lucky to finish the race above critical, and I think that's one of the funnest things to do in RaceBox.