There was some discussion previously about mistaken acceptance, and whether a school could rescind your acceptance. The consensus seemed to be that once you had paid your deposit, they couldn't do that.Deleted
Keep in mind that it is 5K per year for three years. So, 15K total over the course of your training. It's true that this is a drop in the bucket compared to the total tuition costs, but in attending an otherwise unfunded program, I would seriously consider taking all the help I could get.
5k is a miserable offer.
Financially, for that to be worth doing, you would need to have a < 5k difference between your BA salary and your PhD salary. Otherwise, why delay? (and this is coming from someone who is contemplating a 7+1 path). It seems like they are either trying to take advantage of someone who didn't think things through, or someone who was contemplating deferring anyways for personal reasons.
Will you be able to apply to other schools while holding the deferred acceptance to Yeshiva? I'm asking because the year of waiting seems like a good opportunity to get into a fully funded program.