Not too concerned about the mice
although it may degrade the quality of the results, but getting spores through the life support system is something you want to avoid as best you can.
El Reg has never noticed that rodents were too fussy to turn down food because of mold – but that's what's just put a 24-hour delay to the latest SpaceX mission to the International Space Station. The 16th SpaceX resupply mission is now slated for 1316 EST (1816 UTC) on December 5, because NASA staffers spotted mold on fodder …
Went to a talk once by Chris Hadfield who described the delightful processes whereby they are "made empty" (because they might be crammed into the Soyuz capsule for up to 48hrs on the way to the ISS) and then "made clean" with a full body alcohol scrub specifically, as you say, to deal with fungal spores...
"Its aim is to compare the physiology of ageing and its effects on disease progression, by comparing groups of young and old mice on the ISS and back here on Earth."
Depending on the type, mould in food can have a very direct effect on the physiology of ageing and disease progression, the Earth bound mice voted for non mouldy food so now they all have to have non mouldy food.
The mice probably couldn't give a rats about a little mould on their food bars. The problem is that mould spores get into the air distribution system of the ISS and spread everywhere. It becomes very hard to eliminate mould once it sets in because of the sheer amount of hiding space it has in a system like the ISS.
The old USSR/Russian MIR station suffered from mould problems through the later stages of it's existence. The ISS is dealing with it better because of regular cleaning and a requirement in design that nearly all spaces have to be accessible for said cleaning.
Little known fact: After the mould problems on Skylab/Soyuz, the SALT-II Treaty was passed banning the use of FOBS (Fractional Orbital Blob Suprises). One of those cases where the truth was hidden in plain sight, and cover given as a nuclear thing, rather than salt being effective against most small, non-aggressive slime moulds in space. But not the more aggressive mutations evolved in space, and certainly not against 10-tonne blobs dropped from orbit onto New York or Moscow. Banning from orbit was the only way to be sure.
I doubt they'd risk it for a Dragon 2 flight. They're on a time crunch there and I doubt NASA would like them using this booster and risking a failed test (RUDing the booster doesn't give valid results if it happens before MaxQ).
I also have my doubts they'll be able to reuse it in the first place. Musk was very sure of himself when he tweeted, but that's before they've seen the actual booster. That thing toppling into the water like that must have done some damage to the (top) interstage section.
Seems like the towing process has been a little fraught as well, so it might be in salt water longer than they were hoping. Various local Twitter users report that they are using "GO Quest" and a tug to try and recover it but both ships were out all night waiting for daylight, stopping it drifting too far and keeping other vessels away. You can see the tracks of GO Quest here: https://www.marinetraffic.com/en/ais/home/shipid:450521/tracktype:7/lpt:1544041920 which look a little convoluted...