He and Rand Paul got into a highly technical debate about what gain of function was. Fauci was trying to pull a "depends on what the meaning of 'is' is" argument to avoid criminality.
Why do YOU think Fauci was funding bioweapons level research with US tax dollars in frickin' China and not in the US?...and then went to great lengths to cover up the source (his funded lab) when it escaped the lab? The Congressional hearings are out there, and the diary indicates Fauci was lying to Paul. That is why Paul is pursuing this. Interesting that you would feign ignorance on this when you pretend expertise on everything else.