It seems to me you're the one "choosing to be offended by" the article here. As others have said, it is not saying "Tumblr can't do this".

The only two reactions against "Tumblr is banning porn" I've seen are: "This is a dumb move that will kill Tumblr which has a huge adult following" and "The NSFW filters suck and will be overly broad, banning far more than porn".

Both are correct. Tumblr has existed for over a decade and the porn fight is one they've had before, and lost for those same reasons. I don't believe Oath cares enough about Tumblr to be even sort of careful with it, so they're just bulldozing the place into the most standard corporate-approved "social media network" they can think of.

(Disclaimer: I don't care about Tumblr at all, but I've seen enough of these uninspired acquire&bulldoze ploys to recognize them now)

There's nothing "alternative" about your position. There are 3 good faith positions phrased in a casual manner which make no assumptions (except there is a caveat about the effect to users only).

> I disagree, this is not harmful to these users, because ___

(I have a) radically different value system than you

There, you chose one.