He couldn't have been prosecuted just for "cheeky slag" (a Scottish court might have gone for " breach of the peace" which is a catch all Common Law offence and covers a multitude of things) but verbally or physically attacking a woman just for being a woman isn't an aggravated offence. If he'd said e.g" dumb lezzie" that would be.
We did discuss this recently - the fact that hate crime in the UK does not protect anyone who is attacked because of a particular, personal characteristic or philosophy.
It produces anomalies so for example beating someone up just for being a Goth isn't a hate crime; beating someone up just for wearing the school uniform of a "posh" school isn't ( unless there is a sectarian element ); beating someone up just for being poor or ugly or looking a bit odd isn't;
beating someone up just for following a certain philosphy or life-style (but which isn't a religion ) isn't ; beating someone up just for supporting a different football team isn't (unless there is a sectrarian element)
Belgium seems to have the widest definitions of protected characteristics. Belgian law seems to be the closest to the situation where if 1 person attacks another in an argument or a robbery it is a crime, but if the motivation is, or is aggravated by, almost any suggestion of the victim being different from the attacker, it is an aggravated crime.