The “Trump is the president -> you should respect Trump” line requires believing that anyone with institutional power is worthy of some special respect. This seems to be obviously silly when you consider the possibility of some especially evil person acquiring the position.
One may object Trump is not Bowser-level, but the point is that he has to be evaluated on his own merit — he doesn’t deserve free respect for his position. (Yes, the article goes on to poke at Trump’s merits. Those are further, different points.)