It says he was convicted in a Russian-controlled court which is not at all the same thing. International law is clear on this and Russia is clearly breeching it.

Try putting some more effort into your trolling, I quoted the actual appropriate law.

He is a member of the International Legion for the Defence of Ukraine and as such is unambiguously not a mercenary by the definition used in the Geneva Convention and so is owed the protections afforded to prisoners of war.

Specifically, article 47 of Protocol 1 is clear that a neccesary condition to be considered a mercenary is that a person:

is not a member of the armed forces of a Party to the conflict

The fact that Russia has a history of ignoring this is not the knock-out argument you seem to think it is.

What’s a little contravention of the Geneva Convention on Prisoners of War between friends?