Inspired by the realisation he was the only US President to have had a shot, meaning he had the requisite qualifications at the time when the space programme was a thing.
Since he had fighter time and would have been about 31 when Group 8 (aka TFNG) were selected, lets say he applies and is selected.
How does that affect his fathers progression? His own political career? If he has a fairly typical career for a pilot in that group, he flies one or two missions in the 1980's. The Challenger disaster probably kibushes his chance of a Command before his Dad becomes President, which will liklely lead to a permenant grounding.
In OTL he spent several none too successful years in business in the 1980's. Before joining the Texas Rangers ownership group.
Still do it?