If he's spiritual he might have been trying to connect with women who sea swim. Connection with natural water etc.
Or he could have just been wanting a physical session and if you are posting images in bikinis you know, or should do, men will look and the women might be doing it exactly to get a kick of "I'm still hot" and have no intention of meeting up with anyone just enjoying the "attention"
It's social media, it's a load of fucking fake bollocks, which is how I would approach a conversation if it naturally came up if you need an explanation, but really it's nonsense. Although you might find it more difficult to have this conversation as it seems you think it's more important than it should be.
So what, he was single, at home l, had a glass of wine or two and liked a couple of bikini photos perhaps hoping it might turn into a private message "hi Bob how we you doing not seen you in a while" because he was clearly looking for love or at least dating at that time hence he met you. Why not use all the tools the internet provides.
He might end up being a dick.
He might not.
Your relationship might be the best thing to happen to both of you
It might not
OP you can't, well you can, but you shouldn't be judging him by your dick of an ex's behaviour, that's not fair on him.
He liked a few pictures of females in swimwear before he met you. So what? Hardly a crime.
If I was with someone and they started to cross examine my SM use I would run like the clappers. It would indicate to be controlling behaviour, well it would indicate it could become controlling "who's that, how do you know them, they look fit do they train out, are they local" it wouldn't indicate "let's have a bit of fun and get to know each other" I would have no interest in getting to know them.
SM is contributing to people becoming more depressed. Because of shit like this.
If he's nice, you are having a fun time, it's early days I would just roll with it. And stop policing him.