In this country we nod rather than wave. I nod at anyone on two wheels, I started on an FS1-E FFS and therefore am not proud. Some Harley guys are a bit snooty, but most nod back, although this may be coz they don't know what I'm on as more of them are less friendly when stationary at gatherings. Most scooter riders don't nod back but I think this may be partly because most bikers don't acknowledge them and partly because most of them are new to two wheels and are busy trying to stay on or haven't got the idea yet. In the late seventies and early eighties there was a lot of animosity between scooter riders (Mods) and bikers (Rockers) left over from the sixties.
Friends and I used to go to seaside towns in the summer just to have a brawl on the seafront with scooter riders, who were more than happy to oblige. Sea air is so invigorating. I have, however, grown up now.