> you'll quickly learn you can't use it to block political ideology from the DM

That's like, not true at all. The X card is exactly for that purpose, the GM doesn't get a special exception from the effect of the X card.

As a GM, if a player reaches for the X card for any reason I'm obliged to stop and listen.

I'm curious what exactly you mean by "political ideology" in this context. Can you give a concrete example of the kind of thing that makes you uncomfortable?