If the law was changed in such a way that it only ever applied to a specific person sure, but changing laws after someone does something is kind of the way things work. Somebody does a thing, everyone goes “I can’t believe they did that, there should be a law against it” and then a law gets passed or amended. Is that law targeting that specific person at that point? Kind of, in that the actions of that person prompted the change, but it would have been the same if a different person had done the same thing.

Automatic upvote for the Niven reference. I don’t think anything would stop Trump from grifting money from his supporters. It’s like the kobayashi maru, the only options are the least bad ones.

In this case I think they’ve opted to split the difference and take a mugshot proving he’s still being treated like a criminal (although it would have been better to have forced him to wear handcuffs), but not release it to deny him as much free fundraising fodder as they can.

Ultimately as you point out it won’t really matter, they’ll just photoshop something, but at least this way someone will need to put in the effort to make the image and we’ll all get some entertainment about how horrendous of a job they’ll inevitably do.