No, it most definitely is not. The fact that we don't delete everything doesn't mean we approve of it. Sometimes we let it slip - sometimes we're just not around for a minute, and sometimes we just tolerate some degree of transgression of forum rules so we don't have to cut the entire thing short altogether, sometimes we'd rather remove some bits but as the discussion has proceeded, it'd be a lot of work to do a neat job so we just move on.
Don't mistake a lack of intervention for approval. And for that matter, don't mistake a moderator posting in a thread as approval that everything posted in the thread is A-OK.