This is really annoying
Answers
You should report the inappropriate name...
I don't know how/why Niantic could allow these and a simple name parser can weed these out...
Also, at a low level gym, you can just use a low level 1300 Sandslash (level 25 hatched or so) with dual ground moves and go to town. Sandslash is decent HP and great underutilized very common spawn for most folks.
You don't HAVE to get 1000 prestige since it's just 2 more fights vs. a level 7 where you need 8-10k prestige...
There's probably ways to get around name limitations.
I've seen places where you can't write "fuck" and similar, but people manage to write the words anyway, though in different ways.
Sure, it would be nice if Niantic tried to prevent bad words in names, but I doubt there's a way to get rid of them completely.
Also, there's bad words in other languages which makes it even more difficult.
I have it even worse, prestige a gym up to make it stronger and then some asshole throws a random mon he just caught in to get coins. Happened three times in a row, then I was sick of it and wasted two hours and 5 km (Could have been a Chansey candy) to make a fake enemy account just to kick this asshole out.