Legally, I don't know.
Morally? There would be pros and cons. People would be "shut out" on certain days but limiting DAS passes could allow for a better product if it doesn't impact general operations the same way.
This is where the old Fastpass system is missed for many I imagine. My last trip was with the old system and I had prebooked fastpasses for Frozen, Avatar, and Mine Train among others.
I imagine for those with a more mild disability, this level of advance booking would probably work well. You'd know you have access to one big headliner and two other attractions, with an option to book more once those are done. You know in advance what your day looks like somewhat and can go in confident you'll have a decent experience.