What if the committee leaker is talking and said that he was following orders from DiChi and the other Democrats on the committee? Probable cause is a very low standard, even for a Senator. But your typical judge is going to be very leery of signing off unless you have something big, so practically speaking, you are right.
I doubt that the basis for Grassley’s actions is that he has info from a Feinswine wiretap, I was just responding to the notion that there is a FISA warrant against her.
FISA warrant on her chauffeur, she is picked up in the collateral damage. Tough for Difi if she was unmasked as part of the espionage case!