In our SOR banner, I saw a registered cover from the DDR that was sent to Vancouver, Canada. It had the DDR semi-postals for what was then North Vietnam. For those unaware, Scott initially refused to list those stamps stating that the proceeds from their sale were used by the North Vietnamese government to support the war against the United States.
Politics sure do get in the way, sometimes, of permitting us to collect what we want, but I don't think that politics and stamps are strange bed cousins.
Stamps themselves have been used by countries to convey a political message. What more "in your face" could a person get than going into a post office and purchasing stamps and getting military occupation stamps portraying the face of the leader of the country that conquered them? Some stamps were intentionally printed to show international borders of disputed territories that didn't belong to the issuing country. Some of those stamps even started wars. Plenty of stamps issued starting with Great Britain #1 show the portrait of the reigning monarch as a constant reminder of who is in charge. Some stamps are issued to try to gain public support for causes such as independence of break away sections of countries, or to attempt to gain support for lands claimed by another country that the issuing country wants for itself. There are even stamps that show hidden images of a leader who had been assassinated.
Can make for an interesting topical collection - "Political Intrigue".