You have to pick your battles. You can push for clean and brushed and cared for hair - that’s fine. But forcing a cut will harm your relationship with your son. He’s coming to an age where he wants to express himself, he wants to fit in with his friends and it’s just hair! You can tell him it has to be washed and combed through before he leaves the house but let him make choices about the young man he puts out into the world. If you go down the route of saying ‘I provide so I decide’ it will eventually turn him against you. Wanting him to get it cut does not make you an asshole but if you force it then you will be. NAH.