There are no major airports in the Rehoboth Beach area, so if he flew on Air Force One, they would have to land at Dover AFB. From there, it would be about another hour by motorcade (even with the traffic cleared for him) to get to his home at Rehoboth Beach. It would have made much more sense (and leave less of a carbon footprint) to take Marine One from D.C. directly to Rehoboth.
Climate consciousness for thee, but not for me.