Interesting read! Is it regional? Cultural? Perception?
Personally, my bike handling skills suck, especially when I'm tired, and so my hands stay on the handlebars!But I have a good nod.
Older male roadies hereabouts, I've found very friendly as a breed. Nice smiles and hellos. Those that are grumpy; well, I bet they're grumpy everywhere. Our young racing team boys are well raised younguns, and may even nod (they also are well supported by our local bike club) The snootiest seem to be the college boy racers.
When I see another female rider, especially solo, it's a big rush of happy for me and feeling a part of a secrest sisterhood or something. lol. They all, in my selective memory, seem to smile and say 'hello'.
Maybe I have a 'happy aura' from being out on the road, riding. I do love to ride.