Couldn't agree more.
"However, flow necessarily requires isolation. Isolation from design discussions. Isolation from customer engagements. Isolation from iteration and feedback. Instead of continuously converging on what the customer finds compelling, you go forward alone."
Nonsense. Flow necessarily requires isolation when you are focused on a task. It does not exclude team interactions, design discussions or weekly (or even daily) customer interactions. The most productive team I ever saw had quiet individual offices for each programmer, a daily design and status meeting of 15 minutes and a weekly customer meeting.
"I know it’s romantic to think that one person can create an incredible product in isolation. If that’s what you believe, stick to reading romance novels, and stay the heck out of software development."
Also nonsense. Recent history is replete with counter-examples.