The handler knows he is holding a loaded weapon and is on high alert for somebody to do something stupid like kneel down and look the dog in the eye or some such idiocy.
A Belgian Malinois is a dangerous weapon. Sure, they try to socialize them enough to be in a calm stable state when they are around others, but it is not as if there is a 0% chance it could bite the president. I would not want to be on national TV seen as the guy who let my dog bite the US president. I realize the odds are low, but you just never know.
He is not unhappy, he is just on high alert.
The handler knows he is holding a loaded weapon .....
+++++++++++++++++++++++++++++++++++++++++++++++++++++
Trump made a comment about being given the option to have the dog muzzled ... obviously, he didn’t take it. Dogs like that are “serious business” and I’m sure the handler was breathing a sigh of relief when the photo op was over.