Of course he doesn't need to use Twitter to promote his blog. But it is what he is doing, as per the article:

> I’ll still use Twitter to post pointers to ongoing pieces because that benefits me, not Elon.

And that's exactly what makes it selling out for cheap. He doesn't need the traffic; it's not like it's providing his livelihood or anything. But just going by his actions, he still cares more about those hits than about his supposed principles.