Tulsi is #8 and #9 on Trump's platform: https://www.donaldjtrump.com/platform. She was featured prominently in the campaign, along with Elon and RFK Jr.: https://www.vanityfair.com/news/story/donald-trump-returns-t.... Traditional conservatives might not like her, but they knew full-well that she was part of the bargain.

That's just how political parties work! No single faction needs to carry a majority--but everyone votes together fully aware of what the platform is. And Trump kept his promises to his coalition partners and appointed both Tulsi and RFK Jr., and John Thune of all people busted his ass to get her confirmed. (Democrats should try this approach.)