1. The realtor is probably unfamiliar with this sort of arrangement. This type of offer has to be new; it only makes sense after a rise in interest rates and we haven't had that for a while. So of course the realtor tells you to talk about it with a lawyer. Realtor gets free information. Ask your realtor their opinion if you tell them, "If I do talk to an attorney, I'm not going to tell you what I learn." OK, don't and you wouldn't, but use it as a thought experiment.
2. The remedy sounds good but is actually useless to you. Do you want the deed on your house? You do not. You want to sell the deed. So a provision giving it back to you if the Buyer fucks up isn't all that helpful. Especially since the Buyer isn't going to just hand it over. You're going to need a lawyer to sue, and you're not even going to be in state,
3. Even if it's a bona fide deal, why? Didn't you say you're going to be making nearly 750K as a household? If so, why the fuck do you care about getting your full ask? I don't know the numbers, but let's say you're listing at 400K. This offer comes in at 400K; maybe you get another offer that comes in at 370K.
Is it worth the risk and all the potential headaches to get that extra 30K, which is about 5% of one year's income even after tax? I mean, here's one lesson of living an upper middle class lifestyle that people don't often appreciate: the whole point of making 750K a year is that you no longer have to sweat the details. Sure, you can buy fancier cars and a vacation house and everything, but the most important benefit -- in my view, at least -- is anxiety reduction. It's that you don't have to sift through the details of bizarre offers because you don't really need the money. I mean, if you're a climber who wants someday to have a net worth in 9 figures, it's different -- those people live for these types of bizarre offers because money in their pocket gets them hard. I don't take you for that type of person.