I'm not so sure. Let's not forget: the St. George's Cross has been hijacked by racism and hooliganism in England and for many people has dark and violent white / English supremacist connotations. Should it be banned by law for that reason?
In fact, the good old union flag was used last summer in Glasgow to the same effect... The people carrying it were being as hateful, violent and bigoted as they come:
(Yes, that is a Nazi salute, there was a lot of that going on...)
I know it's not quite the same but then what is a flag but a picture? A symbol of a mindset, not the cause or a manifestation of one. I personally don't think any flag should be banned "by law". Not even Nazi symbolism. Stopping people from flying their flags doesn't change their nasty thoughts and opinions... It just hides them. I'd rather let them shout it from the rooftops so that I know what to think of them.