The language is usually "This market will resolve to “Yes” if <politician> ceases to be <Prime Minister/President/whatever>".
Or for another example: https://polymarket.com/event/will-neymar-play-in-the-2026-fi.... Will Neymar play in the world cup? Not if he's dead. Any kind of "will celebrity appear in X in the future" can be reduced to an assassination market.