Wish I could be more help, but (fortunately?) I haven't had to deal with roo squabbles yet surprisingly (since I have a good 10+ roos in a small confined space together). When my girls get violently bossy, though, the ol' "lock 'em in a crate on public display for a day or two" knocks them off their high horse. Not sure if it would work the same for dudes. It's both a blessing and a curse that NNs are so docile it lands them at the bottom of the pecking order. Mine have now taken to flipping the plastic tub nest boxes upside down on top of themselves to hide from the others. Sounds smart, but by the time I find them, they're soaking wet from moisture buildup and almost suffocated.
As for wattles, I'd say keeping a thick coat of Vaseline on and making sure there's ample ventilation, he'll be ok.