Oh yes, some can be pretty snooty on the breed threads, but they are into breeding for the "Standard of Perfection" and that doesn't always make a good dual purpose bird who is fertile, can forage, and is a good lookout for hawk protection, LOL. I have been to a couple of shows where I learned...
He may get lonely being isolated. Is there a way to keep him safe and treat him within the flock? Chickens are quite social birds. You could cage him in the coop for part of the day, then let him out for part before he goes to roost. Reintroduction is a bear as you probably know.
Your cuckoo rooster is very handsome. Could your lavender rooster be having his molt? This could explain his comb shrinkage and acting backward, since molt is very hard on them. The first molt take place about 18 months, then yearly thereafter. Whether he is molting or not, after worming...
Is there another rooster that has taken over the lead position as head of the flock? What did you use as a wormer? Some only get the roundworms and there are are many different possible worms that affect chickens. Valbazen and SafeGuard /Panacur are very good. There could be some internal...