Maybe I don't understand the definition of straw man properly, but I don't think this is one. It's a response to a metaphor some conservatives have used against trans people that the look of a pizza hut is so iconic, that it'd be rediculous to call it anything else, because it's obviously a pizza hut, no matter what you put inside it. This is a response to that, showing that insisting it's still a pizza hut just because it looks like one to you is absurd. I agree it's a little bit cringy. There's been better rebuttals to it, but I think this still makes the point.

I don't think this was ever a popular conservative argument though. I've only seen it in screenshots of a single highly retweeted tweet with various rebuttals attached. I guess it seems more like just a random dumb argument people decided was fun to make fun of.