I'm a motorcyclist and I always wave to motorcycle officers out there. Never seen one return the wave in 15 years of riding, but it doesn't stop me. I assume they're under some kind of standing orders.
I ride a KTM 950 adventure touring bike. When I wave to other motorcyclists, most all of them wave back, except for guys on Harleys. Maybe one out of ten of them wave back, if that. Who's to blame them? They spent nearly $25,000 at the Harley dealership to buy a perfectly good "tough guy who rebels against conformity" image, and they'll be damned if they'll throw it all away waving back at some schmoe on a different bike.
So I have a plan to help them out. One of these days I'm going to rent a Ronald McDonald suit with the biggest red afro and most ginormous floppy shoes I can find, then rent a huge black Fat Boy from Laidlaw's for a day. Then I'll go all over L.A. County, hitting all the biker roads and frantically wave to *everyone* like I just won gold at the Very Special Olympics.