I'll answer that question as briefly as I can, cognizant of the time.
Before I directly address it, I think the government's review of the federal tax code that has taken place over the last year is not just an opportunity to decide which tax expenditures ought to be eliminated or maintained. It's also an opportunity to think about the effectiveness of existing tax expenditures and whether they ought to be reformed.
I would place a disability tax credit near the top of the list of tax expenditures that not only ought to be maintained but ought to be reformed as part of this review process. You've raised the question of whether the eligibility for the tax credit ought to be changed. I'm afraid I don't have an opinion on that, or at least I've not studied it closely.
The question of refundability is a sensible change. The purpose of the tax credit is to help defray the cost associated with one's disability. Those costs don't end when the value of the tax credit ceases. It would be a positive reform, as part of the review of federal tax expenditures, not just to eliminate or maintain expenditures but also to reform ones like the disability tax credit. There are a lot of solid proposals out there to do so.