I personally spotted a mini gun in the back of a suburban following George W Bush in convoy while on his way to speak in Grand Rapids, Michigan, following up... subject matter wise, on his State of the Union speech (delivered the night before in DC.)
The swinging door reminds me of that aspect, as it would give a clearer field of fire, if necessary, to an armed USSS agent, and would provide for rapid egress were it warranted.
Also, a personal friend that was a combat veteran of Viet Nam, was reassigned to a security detail at the US Embassy in Paris, during the Peace Accords between the USA and North Viet Nam.
He has a photograph of himself in business attire carrying an attaché case, that concealed a submachine gun, for diplomatic protection.
I suspect that it is far more likely that the USSS agent pictured in the captured message body has weapons concealed in the briefcase that is circled, than the claim by the original poster that the nuclear football is the primary content.
I appreciate the many contributions found here at the Q thread, but I personally do not subscribe to the notion that P. Trump is the CIC and directs US MIL.