The BBFC is pretty strict on things that they consider repeatable violence, but. Headbutts, for example, are pretty notoriously cracked down on by them. Fist-fights seem fine, but one dude hitting another dude with his head? Hell naw.
Admittedly, no-one's going to go full Fifield on someone else, but the act of stomping or pounding on someone's head is going to set off alarm bells to the BBFC regardless of how quickly edited it is. Australia just seems to care about gross length.