Twitter was a public company.
I'd start with the SEC filings.
Stock prices are a proxy for perceived value.
Market capitalization and all that.
The first question should be, "Has Elmo done anything to change the value of the company?"
I think it's safe to argue that driving away the vast bulk of the advertisers, and thus income stream, means that the answer is a resounding, "He's destroyed the brand and income stream."
Twitter isn't paying their bills either.
Months in arrears on their rent in San Francisco.
Slack licenses weren't paid for so long, the service was terminated by Slack.
Vendors complain of 90 days minimum for accounts receivable.
Not one thing points to a robust and going concern at Twitter.