Standard practice seems to be that one should respect the office, whether that of the President of the USA, Chancellor of a university or Chief Constable of a county, even if you don't respect the woman or man holding the office. However, it seems to me that when the holder of the office clearly does not respect the office herself or himself – as looks to be the case with President Trump – then all bets are off.
What Would You Do in this Position?
Estranged Son and Future Granddaughter