As others echoed it feels reactionary and late but I will support any efforts to stop fake news site from advertising. Hopefully other websites create efforts that stop fake news site from being shared or advertised as well.
They don't decide whether it is news. They just put in guidelines for the websites they want to be in their advertising network. That is totally fair game.
If other advertisers want to fill that spot, they can do so. But Google doesn't have to. It does not impact search results.