I questioned the theory as well. Are they saying the letter was linked by someone in DiFi’s office, and not her personally ? If so , a distinction without a difference. Steffy didn’t want to pursue it, for sure.
Some time ago, this article appeared in the Daily Post. The suggestion was the letter may have been written by a Stanford Law professor. That professor is unnamed.
https://padailypost.com/2018/09/13/eshoo-received-letter-alleging-sexual-misconduct-by-kavanaugh/
It may be irrelevant if true,but implies there has been a great deal of planning and coordination.