When I was putting up "found" ads for the cat, I did a quick glance to check whether we were dealing with a male or a female, and my fleeting impression was "neutered male." Today, I finally took a closer look and thought, "Wait a minute."
Yes, now I think that he is NOT neutered after all. Smöl, but intact.
Obviously, that could change everything, because if there's no one out there who invested in neuter surgery for him, the likelihood that he's just an especially friendly feral kitten is much higher.
I'm going to keep the ads up (with notes about the new observation), but this piece of information means I need to give some thought to next steps that do not involve someone stepping forward to retrieve him.
I am a long-time volunteer with an animal rescue group, so there's a strong possibility that they would be willing to bring him into their program as long as I can foster him until he can be put in front of potential adopters. I'd need to get him tested for FIV/FeLV (also known as a "combo test") and cleared, which I could probably have done this weekend.
Of course, my husband and I have repeatedly sworn that we aren't going to add any more cats to the household (we're currently at "one too many," down from "three too many" early last year). However, I can see that the spouse is getting smitten by our little visitor already, so time will be of the essence in making a decision.
In the meantime, he still appears to be content hanging out in our basement. I've been bringing him some of the cat toys I can't put on the floor in the main part of the house lest they be chewed up by the dog. He seems happy with those and spends most of his time chilling out in the cat bed we gave him.
There's no need to make any quick decisions, but I'm glad he's no longer out in the cold, scavenging for every meal.