Caveat here: If on'e's uncle suddenly began acting in that fashion and it was uncharacteristic, one might seek to have him examined. But if one's uncle has always been an ******* and a contentious jerk, one would probably just accept that he's a jerk and stop inviting him to family dinners.
If Trump has always been like this (an argument made by SG based on publicly available media), and has manged to be pretty successful and even become president, then the argument that his behavior is out-of-norm enough to warrant medical intervention is weakened. It's not like he suddenly because unreasonable, he's always been a jerk.
If,. on the other hand, this is a new development for Trump, and is NOT representative of his historical behavior, then it would definitely warrant concern and potentially medical intervention. This, however, weakens the reliability of a diagnosis based on both current media snippets and historical information about Trump.
Either way... the diagnosis made on publicly available media elements, many of which are taken out of context and have been provided with additional interpretations, are unlikely to be reasonably sufficient to form an actual diagnosis.