You're right, but in an area of crowd containing dozens of lads in their teens/20s, & some adults who haven't grown up, someone is going to react. They shouldn't but they always will.
It's like you waltzing into a scruffy London Rd pub on a Saturday night, full kit, singing Hi Ho. It's not right that you're going to get confronted and assaulted. There's nothing in the law which allows this assault. However it's definately going to a happen. The police would give you little sympathy, because you've deliberately provoked this unlawful assault. Your actions made this inevitable.
Of course celebrating in front of the oppo fans is allowed and part of the game. However staying there & continually gesturing to the fans for a prolonged time in unprofessional & pathetic.