Listen, he already knows he’s just your friend. He dumped you, remember? He’s hitting you up out of boredom - be it for the ego boost or (in his mind) to keep you on some kind of emotional leash in case he ever wants to pursue things with you again.
If you’re only interested in maintaining a “catch up every once and a while” kind of relationship with him, I don’t see what you’d be losing by cutting him out entirely. You can ignore him, but that reinforces what you consider bad behavior.
Personally, I’d just tell him to fuck off.