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.
Knowing the President's habit of going to a specific aircraft and crew and thanking them is something that, whenever and wherever he travels, can be used against him in the hands of the wrong people.
If you do not see it, or agree with it...fine. But it is something that is specific and something that can be exploited. Particularly in a ime of war, such information should always be held close to the vest
You are free to feel differently as is your right.