...if we assume that the May 4 memo ordering Bush to get a physical by May 14 is legit...
According to this post:
Garrett: "The memo also requires a flight physical by May 14th. But military rules set a deadline for flight physicals as the last day of the pilot's birth month. In Mr. Bush's case, that would have been July 31st. All pilots had three months before the end of their birth month to obtain their flight physical."
This also puts the May 4 memo into question, doesn't it??
However, assuming I'm stupid enough to accept Dan Rather's argument that it is legit, the May 19 memo specifically answers that Bush did not obey a direct order, because Killian notes his discussion with Bush about waiting until going to Alabama to perhaps get a physical.