…so they’re inviting councils to remove them, at which point they can say “aha, see you want to repress us true patriots!”.

Similarly, people who object to their street being badly decorated on this manner (flags upside down, badly spray painted roundabouts etc) can be categorised as unpatriotic.

Correct solution is to ignore it for the moment and not rise to it. Let them have their moment, then when the flags start looking a bit tatty or whatever start taking them down.