I can see your point re valuable labour crank and I agree to an extent. I also agree that it'd be nice for NPWS to use their resources to do it, but I don't think that's a likely outcome (going on past experience).
From my perspective Loftus is a series of trails which I don't really differentiate single trail from firetrail. The level of technicality is similar and I basically ride all the main trails every time I ride there. For me that fire trail is part of a loop that has a fun section of single track that gets ridden frequently. The water there causes me as much grief as it does anywhere else, though obviously it's doing less in terms of trail widening/damage.
As I said, I'm happy to hear alternatives. We could start cutting in the diversion around the problem area on the Temptation Creek single track. I'm sort of over trying to fix the lower marshy section. We've expended 3 work days on it, and while it's definitely (much) better, it's not like it isn't crying out for more work (and a trailer load of dirt)
In any case, we won't have to travel far to find somewhere that could do with remediation.