Yes...the fact that the President makes a point of congratulation and thanking the flight crews of aircraft that carry his limo could easily be used and exploited by foreign or domestic enemies seeking to do harm to the President. It should not be spoken of or revealed IMHO.
Dude, I understand that it is best practices to be absolutely silent about everything, but you still haven't given a reasonable explanation for how anything here could harm the president. It sounds like you don't know, but you think they shouldn't say anything as a matter of practice. Fair enough, but just say that if you can't think of how it could harm the president. The fact that he thanks the flight crews could be exploited? Give me one way this could be exploited.