I would keep him safe until you have the Blu-Kote. Then when you reintroduce him, if she goes after him, separate her for a few days to a week. Sometimes this allows the pecking order to adjust and she comes back in at a disadvantage. I have tried this and it worked after a couple days and other times it failed, so I ended up taking the aggressor out for a couple weeks and then it worked. However, it was in a separate coop and run, not in a crate. I just think he will be fine once you have the Blu-Kote. And btw, it's medicinal as well. Usually once I have that on, I just keep an eye on the chicken and reapply as needed. Works for me, and one thing I unhappily have a fair share of experience with is aggressive chickens. All is calm now, but I have 4 littles, so we'll see. LOL Well, I have one aggressor, but she is only aggressive with me. She is actually quite adorable, but every few days I have to pick her up and carry her around for a few minutes to remind her who is boss. She growls the whole time.

I just love her.