He died fighting in battle, after all. Whether he was on the "right" side in that battle or not shouldn't make any difference in Klingon theology. Combatants on both sides go to Sto'Vo'Kor, so Kruge automatically goes to Sto'Vo'Kor too. Of course, there was never any indication that the TOS and TOS movie Klingons actually believed in any of this stuff. They were analogous to real-world totalitarian regimes that didn't believe in religion.
Kor
Some totalitarian regimes don't believe in religion others (like the Talibans) use religion as a weapon to oppress.