I don't think that equivalency holds up at all, because we're talking about things that are inherently wrong and where the immoral aspects are intrinsically part of the appeal, versus something which is fine in theory but full of fucked-up stuff in practice.

I mean, the fact is that pretty much everyone in Western society is complicit in some kind of horrible abusive shit on some level. Whether it's the clothes you wear or the food you eat. But that doesn't change the fact that child porn is wrong and it's in no way a justification for supporting it.