Matched with my brother's friend on Bumble, what do I do?

I just matched with my brother's friend on the dating app, Bumble. Girls have to message first.

I haven't seen this guy for a few years, while my brother sees him maybe 3 or 4 times a year. Do you think it's possible that he swiped right not realising it was me? I mean if he was interested, why couldn't he have asked me out in RL? I do think he's attractive and I wouldn't say no if he asked me out. Should my opening message say hi, it's been ages, and ask what he's up to? Or should I not make it so obvious I know him?