Pretty simple as the title. I’m not asking if you’ll do or say anything that reflects the assumption. Just if you’re aware of it - is your first instinct the assumption that he’s more than likely gay?
Honestly, I don't see too many jockstraps at the gym. There isn't really a functional need for them out on the gym floor. Athletic fitted underwear seems to be the norm, even out on the playing field.
There is a lot of high end fashion/fetish gear in the form of a jockstrap that is definitely marketed to the gay community. Personally, I don't like any of them
at all. Give me a pair of flex/fitted boxers and I'm good to go.
But, insofar as the question, jockstrap = a certain sexuality, then I'd say no. I find a lot of communities wear whatever they want now. I prefer looking at the person, observing their behavior and listening to what they are saying. Outside of outright asking someone, for me it is a better way to gauge what someone's sexual orientation might be.