Not sure about mutiny, because he is not a soldier, technically. He is the leader of illegal but tolerated private mercenary company. (Yep Wagner are theoretically illegal per Russian law)

I am definitely not blaming anyone for calling it "possible coup" or "coup" or even "an attempt to start civil war". The original intent was to explain that coup in quotation marks is also alright term to use.

Edit: every single time I write "wagner are technically illegal in Russia" I get downvoted in HN. It is pattern at this point. So, guys, if that was reason for downvote, yep they are illegal per Russian law.