It sounds like he's made some compromises for you in the last six months. Can you compromise for him for two months? I agree that it will feel like a long time, especially if you're in NRE right now. But any dude worth keeping in your life will wait. Maybe there's a platonic friend or family member you can go to for emotional support during that time? Or maybe you can express those needs to Dan during that time?
From what I understand the partners of MDs have to be willing to make sacrifices. Have you two talked about this?
I agree that it might be a manipulation, but with good logical reasoning on his side. It being a potential manipulation doesn't take away the good reasons for his request. I'd do it, then after the exams ask him to think about why he asked for the blackout. Will he be asking for blackouts again? This is essentially a veto power. Are you willing to allow him this power at times? Can he function as a mono partner with a poly person without that power?