Question regarding developer's need for direct hosting login

Hi devs, question:

I bought a domain name and hosting through Bluehost. I found a developer on fiverr who owns a theme (non-wordpress) that I wanted and I paid for usage, modification, and installation of the theme. He requested my hosting login to do his work; however, I just didn't feel the most comfortable doing so given that my billing information is readily accessible through my account.

I researched online and it seemed like making a FTP account seemed like a way for him to have access to the site while limiting seeing any of my personal information. I made him one; however, he is requesting direct hosting login.

Any reason why he would be unable to do his work with the FTP account? What would the FTP account not allow him to do? Any other options, apart from giving my direct hosting login, that I could provide to him?

Thank you all!

Addendum: I asked why he needed direct login as opposed to an FTP account and he says that it is because database operations are needed and that his FTP client is slow to upload...

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