The article treats short-term sellers as though people are randomly choosing to sell their homes after 90 days.

But that defies all logic. It's almost impossible to turnaround in that time by accident.

People who sell after 90 days were almost inevitably intending to do so all along. Fix and flip is a more reasonable starting assumption.

I guess it would depend if the first sale was brokered by a private individual or by a real estate agent. One would tend to think that most agents would price a home close to market (since they have more information of market pricing than the average person) and prices closer to market would be hard to flip for a large spread in a short period of time.

How do you know it _wasn't_? We basically have a _whole bunch_ of possible hypotheses here that the data/analysis here does not allow us to distinguish.

I don't know, and made no claim implying knowledge. The "what about" attempt (more formally tu quoque) fails.