Not necessarily. It's as equally likely that he does not have any clearances and could not pass a background check, either with the government or the kind that Twitter's regulatory compliance people want.
In the case of companies that do work with the Department of Defense, it is not unusual for managers to have people who work for them who hold clearances but the managers themselves don't. Where I work, we operate a medical clinic in a federal facility and some of our staff have access to federal employee patient data. As a result, some of our physicians and nursing staff have a clearance as does one of our practice managers and some of our technical staff, but no one else does.
Also, remember that Musk has publicly consumed drugs that are illegal at the federal level and had some very visible run-ins with the SEC. Some federal investigators and companies would not have a problem with that, others very much would.
> He most likely has an active TS clearance and works with ITAR.
it's very unlikely (though not impossible for Elon, I guess) that someone could retain a TS clearance after smoking weed in a highly publicized video.
But actually he wasn't a co-founder. He simply bought shares of Tesla 1 year after it was founded.
This is the red flag, so he failed the background check.
True story.
https://en.wikipedia.org/wiki/Tesla,_Inc.#Founding_(2003%E2%...