The alleged transphobia side of this is very interesting, but as Fair Cop have said, this goes way beyond that. It should be of interest for anyone interested in the Twitter joke trial, or anyone on social media who cares about the legalities of what they're allowed to say or the consequences of saying literally anything that anyone disagrees with.
Despite their efforts, it's not all about the trans ...
This case goes to the heart of general police behaviour and the ingrained attitude they have that they can do what they like "because they is plod". There have been plenty of instances where law abiding people have been approached - having committed no offence - by police who have decided to throw their weight around.