Hey diaper boy mke, nicely handled! If you choose to talk to him, I'd recommend getting to know him as a person for a bit before moving on to diapers. Just like how it's not really first date material, it would make a guy super nervous. There was a time I would have Freaked if anyone, even another DL knew what I was into. If you get a good vibe about him and he gets a good vibe about you, then address it like the cool, quirky fun it is.
I know it's pretty important to inform this guy about appropriate outlets for his sexual energy but part of that is showing that well adjusted, nice, respectable folk are into it too.
Thank you for trying to reach out to another human being in a time in history where fear controls too many.