Just after Musk expressed his concerns, Twitter announced later Tuesday morning that it is committed to the deal at the pre-agreed price, adding that it has submitted a proxy filing to the SEC. The company's shares slipped 2.46% in premarket trading Tuesday. A spokesperson for Twitter did not immediately respond to a CNBC request for comment. Musk's tweet comes just a few hours after Parag Agrawal, Twitter's CEO, posted a lengthy thread about spam on the social network.