to clarify.. Technically, I think this would be tenant responsibility because he/she/they totally messed it up. But then again, you really don’t want the mold to accumulate.. Most tenants don’t give a crap since it’s not their place, so they won’t have an incentive to keep the bathroom carpet dry…
Tenants can be a unreasonable PITA in other cases. In this case, it’s not that you’re trying to accomodate the tenant…You’re protecting yourself from more expensive water/floor damage if carpet stays.