I think we're on a border somewhere (but I'm not sure which side of it).  Obviously we don't have all of the facts but it sounds like all of the other requirements are met for a QC dependent.  If you run through the ITA looks like he qualifies.

The question in my mind aligns with Bill's thinking here.  Since the post mentions disabled I'll assume that condition has been met (I'm under the impression it's not too hard to get a doctor to sign off on these things).  So that leaves us with the mystery of "substantial gainful activity".  I couldn't find an IRS "bright line" for this but did find the same thing that TGB found on ssa.gov, with $17K slightly under 12x the monthly amount for 2024.