I just do not get why everyone on a bike think they need to wave at each other. I do not drive down the road in my car waving at everyone else in their car....
Eh. You're trying to account for human behavior using logic, and people are anything but logical. Some riders wave at every passing motorcycle. Some riders won't wave at anyone. Some riders will wave from a thousand yards away on a split freeway. Some will only wave at others who ride HDs. There are days I wave at everyone, and days I don't want to wave at anyone. Heck, I've had bicyclists wave at me (and yes, we're still talking the low-peace sign thing). I've had riders wave at me when I'm in my car, which I have yet to figure out.
Do what feesl right to you, and don't worry what others do. Since these people don't know you, a wave, or no wave, is neither personal nor truly meaningful.