Perhaps you read a different blog post than I did, but that's not what he signalled at all. He regrets getting involved with ESPN specifically because it was a poor fit for him as a television network that didn't have a suitable business model for 538, and would have preferred if he had taken the competing offers from NYT or Bloomberg in 2013 and then wanted to move to The Athletic in 2018. At no point did he say anything like "I wish I didn't sell 538 and stuck it out alone".