Not in the public interest? Want to assault an unconscious man? Go play Rugby League, you'll get a ban from playing but no actual punishment? I'm amazed we haven't heard from Greater Manchester Police... yet.
I hasten to add this isn't about the first punch, it's about the follow up.

i dont believe they would. A punch is a well established part of the game (rightly or wrongly) and there is an expectation of its possibility. What Flower did is entirely different.

I'm not saying the complaint would get anywhere. They would take the nature of the sport, and its governing body into account and likely dismiss it.

A punch is a well established [itransgression[/i. That isn't the same as it being a part of the game. Either the police are duty bound to investigate a complaint where an assault has occurred or they are not. They could not, without any impropriety, investigate Flower without investigating Hohaia.

Just because you have set up a false dichotomy, doesnt make it true.

The police/cps would only be bound to move forward such a complaint if a reasonable person would not expect such an offence to happen during a game.

Who told you that, and why did you believe them? There are lots of scenarios where one might reasonably expect a crime to occur but it does not relieve the police or the CPS from their duties to follow it up. The assault Flower committed occurred in the context of he himself being assaulted, albeit to a lesser degree. There is no way any investigation could turn a blind eye to that.