Only for it's DNA, and I'm sure Stamets would've scanned the Tardigrade DNA & mapped it's entire genome sequence and know what to look for.Which circles back to needing a tardigrade.
I'm sure with the resources of Section 31 outside of the UFP, they would've found a Tardigrade eventually & re-created it.
Doesn't mean Section 31 is inclined to help StarFleet save Voyager.
Remember, Section 31 by that time has been long kicked out of StarFleet Intelligence for over a century.
So they have no obligation to help StarFleet in any way, even if they could.