I don't understand why I would ever side with Tanzawa on this matter. I was hesitant at the beginning because of how good of a guy Yoshiki is, but now it's pretty much confirmed. No matter how good of a guy Jou appeared to be to Tanzawa and friends, he was a terrible person that did unforgivable things; which, in my opinion, makes Tanzawa complicit in those actions.
But maybe that's the point. We were supposed to see Tanzawa earlier in the series as he saw Jou. I don't know, just spitballing.