Being disabled is an exception to the early-distribution penalty that would otherwise apply. The code 3 in box 7 of the Form 1099-R indicates that this penalty exception applies. It is not an exception to paying income tax on the distribution.
TurboTax is asking what the normal retirement age is for the plan. When you are under the normal retirement age for the plan and receive disability payments from the plan, the payments are reported on your tax return as wages instead of as retirement income.