So? That doesn't actually affect my point. You'll also note that he started being a cool dude before Abelhem died.As Orbmorb noted, Kasmir was initially the opposite of open-minded:
And just to be clear, he'd started to be more openminded too. The Morrite recruitment for the army for example, but he'd even reached out for Ranaldians, which is going the extra mile. He wasn't the guy who decided it's best to put the swamp god in charge, but he was already the guy on the journey there, and I think he'd have gotten there either way.
As far as Mathilde was concerned, Sigmar betrayed him too in that whole mess.