Personally I would hold off filing anything until closer to the extended deadline.  I suspect there are still rules to be written, no point in rushing to file something just so you can amend later.

If nothing gets changed and the IRS ruling stands, I would be inclined to report a negative expense to get the taxable income correct.  I could pretty easily be talked into reducing individual expense categories though.  From a QC standpoint, salaries are already going to be a PITA to reconcile for 2020 with COVID pay thrown into the mix, I'd rather avoid having NDE as an additional reconciling item.  But they don't let me make the rules.