The use of "a" instead of "the" pilot suggests more than 1 personnel on the plane, considering F15's carry 2 people (unless it's some magical F15 I haven't heard of), it means there's still 1 guy missing out there.
Or he (I assume) could also have been found dead, and is not being mentioned before his family is notified of the sacrifice Donald Trump made of his life.
F-15 A and C are single seaters. C is actually the most common variant the USAF has.
The one shot down was an E though so two people.