And it is rude to expect people to proofread your slop.

The author isn't defending slop, in fact they hate it too:

I utterly hate AI-generated content. I don’t want machines to replace personal writing with synthetic filler.

What they are arguing for is AI assisted proof reading tools, particularly if English isn't your native tongue:

But a spell checker doesn’t make a post fake. Grammarly didn’t make old posts fake. A machine helping a non-native speaker write more readable English doesn’t make the work fake.