So Scott the psychiatrist's reputation can take a hit? If Scott Alexander writes shitty stuff, Scott Alexander's name will take a hit. And there's nothing wrong with that, because his future work will also be published under that name. But what's the rationale for nuking Scott the psychiatrist? (who will also be nuked even if his patients see nothing wrong with his blog. Patient-psychiatrist interactions are supposed to be tightly controlled)
Colleagues, sure. Patients, NO. Especially since this will harm even potential patients who would have had no problem with Scott. The problem isn't that patients will read SSC, decide that Scott isn't cool, and Scott loses business. It's that patients will read SSC, learn too much about how and what Scott thinks, and this will hinder Scott's ability to help these patients regardless of what said thoughts are. For instance, if Scott talks about hating PE class in high school (he very well might have, I don't know), that could stop patients from opening up to him about their passion which happens to be sports or something.
But, you say, surely that's not a problem for well-adjusted people! Guess what the hell a psychiatrist does.