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SAN FRANCISCO, CA - OCTOBER 09: Twitter CEO Dick Costolo speaks onstage during 'Social Goes Global' at the Vanity Fair New Establishment Summit at Yerba Buena Center for the Arts on October 9, 2014 in San Francisco, California. (Photo by Michael Kovac/Getty Images for Vanity Fair)
Dorsey had been acting as "interim CEO" for three months after former CEO Dick Costolo stepped down in July, because Twitter's board of directors said they were looking for a replacement who could focus on the company full-time.
That made Dorsey a suprising final choice, because he's also the CEO of payments company Square, which will go public later this week.
In his first interview since Dorsey's appointment, Costolo defended the CEO selection decision on CNBC after the host said that Twitter couldn't find anyone else who wanted the position.
He called the idea that Dorsey got the job because of a lack of other options "nonsense."
Here's the slightly awkward exchange:
CNBC: The search took seemingly forever - more than 100 days - and there was a suggestion -
Costolo (interrupting): There's a difference between "100 days and seemingly forever." Three months.
CNBC: ...Okay but there was the suggestion (and there still is) that the job was hard to fill. That nobody wanted the job. And that's why Jack got the job.
Costolo: That's nonsense. The board wanted to talk to a number of people. It wanted to cast a wide net. It wanted to be very thorough in the kinds of folks it talked to. There was a significant interest in the role from a variety of executives. But again at the end of the day we came back to, Jack is the person that best understands what we need.
Costolo also said that Dorsey is right for the job of leading Twitter because he has the "moral authority as the inventor of the product" and understands it deeply.
Later in the interview, Costolo also teased the announcer for misprounouncing his name.
In case you've been struggling, it's "Cost-OH-lo" not "COST-uh-lo."
Watch the full interview here: