Dr Fauci revealed he kept portraits from fans on the walls of his home office, and told the Times he was reluctant to share the personal insight after being previously attacked as an “egomaniac” by the far right.
“Creepy,” Mr Musk wrote on Friday. “Maybe he just loves looking at science?” he added.
It’s the latest in a series of personal taunts the Twitter CEO has directed against the 82-year-old infectious disease expert.
This week, Mr Musk tweeted: “New Twitter policy is to follow the science, which necessarily includes reasoned questioning of the science”.
The post was widely interpreted to be a slur on Dr Fauci, and came after Mr Musk had made a transphobic comment that his pronouns were “prosecute/Fauci”.