Asked if Musk has proven himself to be the best possible steward for the platform, Dorsey said, “No. Nor do I think he acted right after realising his timing was bad. Nor do I think the board should have forced the sale.”

After stock markets turned shortly following his offer to buy Twitter a year ago, Musk sought to withdraw from the deal. That prompted a legal battle between the company and the billionaire, before the acquisition was completed at its original offer price.

“It all went south,” Dorsey wrote on Bluesky, the invite-only Twitter alternative that he’s backing.

Twitter did not specifically respond to a request for comment.

Dorsey, who was friendly with Musk for years and suggested he get involved with Twitter, was previously publicly in favour of the deal. Last year, he called Musk as owner of Twitter “the singular solution I trust.”

On Friday, one Bluesky user said it was pretty sad how it all went down, to which Dorsey replied “yes.” But Twitter “would have never survived as a public company,” he added in another post. “Would you rather have had it owned by hedge funds and Wall Street activists? That was the only alternative.”

Under Musk, who took over in late October, Twitter cut a majority of its staff and endured a number of public crises, including over its plan for verifying users. Musk has been pitching a subscription service for Twitter in which users can obtain a blue check mark for US$8 a month.

“Payment as proof of human is a trap and I’m not aligned with that at all,” Dorsey said on Bluesky.

“The payment systems being used for that proof exclude millions if not billions of people.”