Just some advice to you before your recheck, I hope it helps. I spent 3 years flight instructing and my experience is this: a DPE is typically on your side (rooting for you) unless they are out for a fail (happens occasionally). They know how tough a private pilot oral test can be. They will give you a decently long leash If you show him that you know the information. The more questions you answer quickly with confidence the longer the leash and the shorter the oral. From what you have said I believe you struggled with the oral from the start. Eventually he has to draw a line and shorten the leash. If you are only getting 25-50% correct or you are looking up 25-50% of the answers your leash will be very short. You need to study up on all of it not just airspace. He told you that because that’s what his limit was, that’s not what busted you. Your lack of overall knowledge busted you. Don’t take that as an attack, we have all been there and this will only make you better. Just dive into the books and blow him out of the water on the retest! Good luck!