Why is he doing interviews like this?
That is a very good question. Fauci has repeatedly stated that only anecdotal evidence exists regarding hydroxychloroquine and azithromycin as a treatment of COVID-19, yet more than one paper describing clinical test results has been published, including one by French virologists who are peers of his expertise wise.
Fauci has been so busy working the PR angle and getting himself on TV that he hasn't taken the time to read the latest research papers. Trump is probably more up to date on the science than Fauci, since Trump listens to and watches what is actually happening in the world.
While Trump is busy managing the response to a world wide disaster Fauci is thinking about how he can make himself look good.