Ukraine is a messy country fighting to keep their freedom from Russia.
“Could be as simple as someone had an axe to grind against him.”
That would be my assumption as well.
People often want to attribute these things to political differences or some sort of ideological struggle, when most murders are for person resentments and grudges.
And the uncontrolled free-for-all that prevailed in the Kiev area in the weeks after the war - they gave out AKs to everyone and there were murders every night that were covered over as “executing traitors” but were much more likely gangland slayings and score settling.