Theres a long tradition of leaving confidential stuff on trains unsecured, i doubt that theres much in the red box that would cause embarrassment as
its probably just speeches and supporting crap for them and i doubt you'll find letters from Marvin the martian asking if you can have a word with
Obama to stop NASA drawing willies on his planet etc
Hang on a second, we do not even know if the red box was empty or not, which is kind of a crucial point. If there was nothing in it at the time, then
it doesn't really matter whether he left it or not. On the other hand, if there was something in it, then major mistake!