I fed him Wednesday and Thursday night.
I have not seen or heard him Friday or Saturday night.
The nights he was there to eat, he came out quite quickly to eat. I called a NPO shelter/adoption (they're quite established and I've donated there several times) to ask if they might be able to come out and trap and rescue him... they told me they need to see a photo of him first (they need to establish his age - apparently this summer has produced many kittens). So I've been putting the tuna out and "hiding" crouched down the street, camera in hand, but after 45 minutes or so I go into the house to watch from the window just in case he's nervous I'm there - I just want him to eat. I leave the bowl of tuna at the side of my house all night. I know other cats must be coming to eat - and in fact, one left a big stinky "thank you."
I hope he's eating it, too, or that he's found someone else to get him food.
I guess I'll continue to try feeding him from 8:30pm as usual for the next week or so to see if he might come back to eat.
Fingers still crossed...