I'm gay, that doesn't mean I want every guy in the steam room looking me over. On here that is fine (more than fine, hehe), but in person I wouldn't want someone checking me out - especially to the extent that this guy seems to - unless I was up to it.
I'm also confrontational, I through elbows if you grab my ass (hey, i'm a top) and will ask if someone has a problem, or if they mind looking in another direction. A lot of times i'll just write something, like a sign, or trace NO WAY clearly, if they are looking at me, they now know, if not, they won't notice. If I tell someone to look away and i'm wrong, well first, I won't really know because they almost always try to deny it even when very guilty, and second I really don't care what a stranger thinks, if i'm wrong they will get over it quick.
I think my aggressiveness stems from a situation similar to yours, except I was 11 or 12 at the time and the guy frightened me, he followed me around and the final straw was when he came up next to me at a stall when I was peeing and looked directly at my peepee (I say peepee as I had not started puberty). Some people are just creeps and don't care if you are uncomfortable with it, they will keep doing it until you assert yourself and stop them. The whole "they are just shy" or "afraid to approach" thing is B.S. This guy clearly has no problem going for what he wants and is fine with your seemingly obvious rejection of him.
It sounds like your lack of reaction, your passive behavior toward his lil'stalking routine, is seen by him as an invitation to take it a step further. He may also know you ae uncomfortable and get off on that, I mean people post stuff on here about following guys or flashing guys and assuming that the person enjoys it as much as they do (seriously, there are a few delusional people that think the world wants to see them, people that are into that, like many of us, make up a pretty small percentage of the populace, but when we surround ourselves with similar folks, we start to think everyone cts that way) - when in reality that is rarely the case and the exposure is very unwelcome (unless it is a welcoming setting condusive to that behavior such as a bathouse). The stalking is just sort of a reverse flashing, so to speak.
I know I have been flashed when going about my daily routine, and it is just kind of like "eww, go away" whereas in a different setting I would probably be turned on. I will "accidentally" flash friends, but only with ones I know well and with ones that I know would like to see it (generally the ones that ask questions about it) but I don't whip it out assuming it will be appreciated, conversely I do not assume that everyone wants me staring at them. I've been stared at before, sometimes I like it, sometimes I give them a look that tends to frighten them off (i'm not real muscular or anything, as you can see, but I am tall and have a very menacing mean look, or so I have been told, haha) Thus I come here, where may of us are here for such purposes.
Really, it boils down to the fact that no one really wants someone that turns them off to check them out, it kind of kills the mood.
....my god i'm long winded. My apologies.