Tom wasn't much of a superhero. Not yet, at any rate. He could fight okay, but he was nowhere near where he needed to be to do what most experienced superheroes could. He also hadn't picked up much in the way of tactics. It was why most of Magog's arguments with his dad sounded like gibberish to him. Both of them were military men, though dad did his tours back in World War II and Magog had been serving in the middle east when Jay and Alan had recruited him. So a lot of the normal superhero stuff was still lost on him, even if he was slowly starting to pick things up.
One thing he could do, could do in spades, was think on his feet. Even before mom died, she'd been a busy single mom, so a lot of the day-to-day stuff fell to him. Thinking on your feet was pretty much necessary for taking care of yourself, especially as a kid. Schedules changed, life threw you curveballs, and you either rolled with them or you ended up in a bad way. So when he realized this conversation wasn't one that they should be having on some random street corner, he rolled with that. "Oh, y'know. I'm a tourist, just passing through."
Luckily, he was nearing the end of the song, and with a last few chords he brought it to a close. Then he stood, nodding to a few people that had stopped to listen, and said, "Sorry, folks. Fifteen minute break! You know how it is." Then he bent over to fish the money out of the case. Not only did it turn his long hair into a veil for his face and, more importantly, his lips, but it also succeeded in bringing him close enough to Kitty to mumble, "Probably not a discussion we should be having on a street corner. Diner down the street, table in a corner?" Maybe it was a little paranoid, but it was better to be safe than sorry, especially if there were demons around. No reason to let one of them overhear him branding himself as some newbie without any idea what he was doing. He might as well stamp "easy prey" right on his forehead.