There are the quarantine issues to consider. I assume you know about that. I'll go through a bit anyway.
If the rooster is coming from a stable environment, which means it has not been introduced to other new chickens in the past month, quarantining him by himself is pretty useless. Either flock could have diseases they are immune to but they could infect the other flock. If he is immune to something, you can isolate him for years and never see any symptoms. If he is coming from somewhere that he has been exposed to other new chickens, like a chicken swap, then a quarantine is a good idea. I don't quarantine since the only way I add new blood to my flock is by getting hatching eggs, but if i did, I would put one or two hens from the existing flock with him in quarantine to see if they infect each other. This way I would risk one or two chickens, not the entire flock.
For what I think is your basic question, I would just turn him loose with the flock. You are dealing with living animals so anything is possible. It is always possible your hens will pick on him, especially a less mature rooster with mature hens, but the odds are that he is mature enough that he will WOW them with his tremendous looks and personality and just step in and take charge.