I only say this based on him seemingly having owned the meme - his intro line on The Delta Flyers pod is "The Forever Ensign" - it may be that he was happy continuing the joke?Kes was problematic, given Jennifer Lien's issues. But since PRO had access to the Delta Quadrant, they could have given us an update on Neelix. And not including prime Harry when Garrett Wang was so available and so eager to be involved was just stupid.
I did really like the older (kind of Pic era) version of him we saw in Timeless and then as Capt Kim in Endgame and would be very open to seeing grown up Harry but if it is just a 30 second cameo (like Shelby) I'm not too fussed but if he got a full episode like Ro then I'd be down