These are all really interesting questions. I'm always open to readers interpreting however they want to.

These are my takes: Rodgers is 100% full of himself and not scared of Harry directly. He was/is very alarmed about having someone in the office utterly borking the politics of it by having undue influence to throw around to get their way/get out of trouble. Rodgers would prefer to handle things his own way. Fear of loss of complete control over the apprentices and their training is pretty much most of what's going on with Rodgers with regard to Harry. His first plan was to make it clear to everyone that Harry wasn't suitable. I don't think Rodgers thought imagined/imagines he could be fired for threatening to imprison snape. Even if he thought Harry might throw all his influence into it, I still don't think Rodgers would ever imagine it'd come to that. He's the kind of guy who is certain he is in the right and everyone will recognize that. That he backs down is mostly due to the influence of his peer group who manage to argue there is gray area there and that keeping Harry happy is worth dropping it given said gray area. For now, that is.

This is a nice square meal of a chapter, isn't it?