My old crush from High School has matched me on two different dating websites...?

tl;dr: My high school crush from over 10 years ago matched me on Tinder after liking me on OkCupid years ago, but doesn't seem interested in me(?). Why is he liking me versus messaging me on Facebook if he wants to talk?Maybe you guys can spell this out for me because I don't fucking know at this point. So to give some background:About ten years ago, I had a major crush on this guy a year younger than me in HS. During my junior and senior year, we were friends in passing only. We had mutual friends, we were both gay, but we hardly had a long conversation nor did we hang out. I remember we talked once on either Facebook or Myspace and I mentioned that we could both be teaching together or something. I did have a crush on him, but it wasn't as serious as the other crushes I had. I've always had feelings for him (I still do), but I never was sad or cried over him (as I did my other crushes).On Valentine's in my senior year, they had this thing where you can send anonymous serenades and cards and I made a cringy card and sent him one anonymously. He figured it out, but nothing seemed to come out of it, and his friend told me that he didn't seem interested, so I was like okay whatever. For some reason, probably because of the card he unfriends me from Facebook so that was that.My memory is even more fuzzy after this point, but five or six years later he sends me a like on OkCupid and he messages me. We catch up and he comes off to me as a little...obnoxious at this point? I remember being a little annoyed that he was touting his achievements and himself mostly while asking very little on how I was doing. I remember asking why he decided to talk to me on here (a dating website instead of you know...friending me on Facebook and doing it through there?). His response was something like "Oh I just wanted to see how you were doing." And we kind of left it there. Few months later I found him on Grindr, I said hey but he never responded. So I just said fuck it. I didn't really care since he was just an old high school crush.Fast forward to today. I'm swiping on Tinder and I see his picture for the first time in like two or three years. I think to myself "There's no way..." So for shits and giggles, I swipe right and to my utter astonishment and confusion he liked me. He liked me first. So now I'm sitting here wondering whether to say hey or just wait for him and what this kind of means? Like why does he choose to talk to me and like me on all these dating sites but not say hey on Facebook and friend me?