Here's a good explanation from u/Throwawaycuzmeh:

Kotakuinaction's mission statement was opposition to censorship and bad journalism. It is impossible to oppose these things without opposing leftism itself. Virtually all bad journalism and censorship is coming from the left. So the sub began to organically tilt conservative.

The mods leaned more left, and they became obsessed with making sure the sub did not become "another T_D". So they implemented a ridiculously vague rule of "no unrelated politics". They then used this rule to remove content that was absolutely relevant but supported conservativism.

At one point, the mods actually put the rules to a vote. The users overwhelmingly opposed the absurd content removals. The mods didn't care. They ignored the results of the vote and continued arbitrarily removing content. Some of the mods became openly hostile to the users.

On a related note: the Kia mods lost their shit when users started talking trash about polyamory. I can't imagine the mods would have behaved this way unless one or more of them were engaged in the polyamorous lifestyle. We might have been dealing with literal cucks.

Credit to u/Ragnar_Danneskjold for putting it in the KiA2 announcement thread on thedonald.win