Got it! This makes a little more sense, because they are asking for all 4 years up front, or the first two years, with a third party guarantee for the balance, which you neglected to mention in your OP. The reason for this is that a non-citizen or permanent resident is at a greater risk of not receiving guaranteed funding in the future, since you can't access federal guaranteed loans. This sort of guarantees that you won't withdraw for financial reasons, at least for the first two years. They do need this, because, if anyone leaves, they are stuck with an empty, non-revenue producing seat, plus it represents one less doctor being created to meet the doctor shortage.
I'm just thinking outside the box here, since you asked for ideas in your OP
, but, do you actually have private loans lined up and approved, which was implied in your OP ("I just found out the school won’t certify my private loan.")? If so, an effective work around might be to explain the situation to the lender and receive a 4-year guarantee to originate the loans, subject to a disbursement schedule dictated by the school, contingent on the school certifying the loan.
Another thought might be to ask the lender to fund all 4 years up front due to your unique situation, again, subject to loan certification. This would cost you a lot more in interest, which should make the lender happy. If the lender is willing to work with you, you might even be able to negotiate a discount (partial scholarship) with the school to compensate you for the additional interest you will have to pay.
If the school won't acknowledge that your situation is very different from that of a wealthy foreigner with the means to pay upfront, and is simply unwilling to work with you, then, unfortunately, the acceptance was a mirage, and my advice would be to get your Green Card and start over. It's easy for me to say since I am not in your situation, but, if any institution, f***ed me over like this, I wouldn't want a deferral in order to kill myself obtaining money just to hand it over to them!
If you take the time to build a stronger application while waiting for the Green Card, you are almost certain to have better results, because you will also be able to apply to the universe of schools that wouldn't consider you as a DACA. There are relatively few citizens with the means to fund 4 years, out of pocket, upfront, and NYMC knows this, which is why it's not required.
Their policy is designed to guarantee payment from foreigners, and, by definition, closes the door to all but the wealthiest among them. It is highly unlikely that any DACA could do this, and they HAD to know this. If this was an oversight and they are unwilling to fix it, F--- them.
Trust me, you have overcome obstacles your entire life. If you stick with it and keep working on your application while awaiting your Green Card, you will ultimately have a much stronger application, with a really compelling story to boot, and will have much better options than NYMC, with access to federal loans, if not outright need-based or merit scholarships.
I'd never reward NYMC with my money down the road if they refused to do the right thing now (i.e., granting an exception involving institutional loans or loan certifications to fix their mistake by not giving you the proper guidance up front upon learning you are DACA). Seriously, where the hell would they expect a DACA to get 4 years' worth of tuition, fees and housing up front???
One more thought (if you have to use it, I expect a shout out on CNN!
) Given what's happening now with Congress seeming to come to a consensus that some path to citizenship has to be provided, as a last resort, if all else fails, I'd ask NYMC if they thought it would be a good look if you shared your story with the NY and national media. I wouldn't be surprised if someone thought this might be a story worth telling. I also wouldn't be surprised if NYMC wouldn't want to be in the middle of it. ("DACA recipient overcomes all odds and receives an acceptance to medical school, only to be unable to attend due to federal policy prohibiting DACA from accessing federal loans, and greedy school being unwilling to certify private loans because it wants all its money, in cash, up front.")