I think he's going to be rude like the past rivals :( Just from how he looks I don't think he'll be necessarily friendly to the others. As for the other protagonist I'm pretty sure they will be involved, to kinda... get even with what B/W had, sorta. Kinda disappointing if so, I wanted a really nice rival!
I'm kinda th opposite - give me a guy I'll like to hate and I'll be happy too, as long as the rival has an actual personality with a dash of character development. They can do 'nice rivals' fine imo (Biana/Cheren) and so too the not so nice guys imo (Silver/Gary). THat's the main thing I'm concerned with - he can be whatever he pleases as long as he's an interesting guy I'll enjoy beating up.
Guess it's a bit too early to think much of him based only on his look and not knowing the context of his quote there, beyond 'what hair stuff does he use?'. =p