I thought se can
他要不要 instead of 他要。。。吗
Maybe it's different because it's phrased as "doesn't he want..." as opposed to "does he want..."
My only reasoning for this too
I got caught too.I think when you word it that way you are saying does he or doesn't he want it.
It tricks you by saying 不要
I thought to negate 要 you should use 不想 instead？
Why is 想 not allowed to be used?
要不要 can not use why