This sounds like one example out of many? Disclaimer: I don't know the involved persons and their personalities, and I'm only a remote spectator to the whole thing playing out in the US. But here is my take at the issue:

There is a increasing divide splitting the American people, and the fronts are hardening more and more. I know a company is not a place to heal the nation, but the wider the gap becomes, the more difficult it becomes for the people to actually discuss their views and develop understanding for one another - as opposed to yelling at each other (and "F* T." is close to that).

Whatever your stance on that EO or T. or the whole state of politics is: I think instead of outright banning discussions of politics (or are violations against the CoC not enforced?), you should maybe try to foster a culture of "you're neither required disclose your political views nor to participate in political discussions, but if you do either, be constructive and accept that others might have a different opinion.".

(Or something in that general direction - I don't have too much time today to produce a nice and watertight formulation of this ;-))

I don’t think there is anything preventing them from defending him or EO13769 is there?

I don’t quite see how they could effectively do that, but the possibility is there.

(Yes, I realize it would be social suicide, but while I understand that this is theoretically a bad thing, I just cannot quite apply it to Trump supporters)

> I don’t think there is anything preventing them from defending him or EO13769 is there?

The new ban on politics would ban them from defending Trump or EO13769 in the workplace. Before the ban they could have defended Trump and EO13769, and the following discussion would have likely devolved even further than just "'F* Trump', written out".