I was thinking along the lines that evidence already exists that would provide much the same value as the access logs might, but the access logs would either provide cover for introducing that evidence, or provide the value without disclosing other surveillance methods.
Either of those prospects is troubling.
The subpoena, and USA Today's response [1] paints a picture of an incompetent and/or inexperienced FBI agent, who is unaware of existing Justice department guidelines specifically prohibiting her from serving such a subpoena.
Reading between the lines, citing "other methods" is the FBI's way of quietly withdrawing a subpoena that should never have been served.
[1] https://storage.courtlistener.com/recap/gov.uscourts.dcd.231...
> "The subpoena is being withdrawn because intervening investigative developments have rendered it unnecessary," an FBI spokesperson said.
I think this is nothing like a "mea culpa", but instead has absolutely everything to do with managing the establishment of precedents to work in the favor of the FBI whenever possible.