If you are swapping it out with another OEM one, just remove the elbow fitting from the BPV (two or three screws, IIRC) and mount that to the new one. That way you don't have to remove the hose.
I can't really think why that hose would be hard to remove, but I see you're in rust and corrosion country. If the suggestion above doesn't work for you, try spraying some PB Blaster or similar in there, wait a few minutes, and use a pair of channel locks to give the hose a twist to free it up. Then it should pull right off.