On the flip side. Maybe the person riding along , is sick of people and simply wants to exercise in peace without having to wave every 2 mins at every passing cyclist.
I do acknowledge riders if I’m crossing paths with someone who looks like they are out for a leisure ride or if they gesture towards me. On a sunny summers day I simply won’t bother as I’d be like a nodding dog. But if I’m out in the depths of winter , freezing my balls off - and I see another poor soul doing the same - I will deffo give a nod of mutual idiocy.
But just because someone is riding a bike , doesn’t suddenly make us amigos. Imagine if every car driver wanted a wave as they pass you , and also needed to have a look at what your wearing