Board Game Arena

How are we supposed to react to Kingmaking?

The site suggests a public red thumb, but if you try to give one, it erroneously reports that it is a player''s first game, despite them having 300+ ELO.

Players can (and do) engage in Kingmaking without repercussions.

Reload the player's page and try the public trick again.
I think the "first game" thing is an error, since you say ELO is 300.