I also wave to everyone, especially guys who wave first. Once in a while I have my hand on the clutch, but I nod. I even initiate a "two low" wave to scooters. It costs nothing.
What I fear in some of us is the idea that since it's a Harley we should act proud or tough or sadly both. I'm a patch holder, I got that stuff done decades ago.
I am concerned about the simple stuff. For example, I stop for bikers along the side of the road. If only to lend them a cell phone. Even for a crotch rocket. I'd want them to stop for me.
If we start building a "wave is beneath me" standard then sooner or later it will be our turn. A wave is cheap. Your biceps and your rep are still intact, but your clutch cable might be fraying...