I have found a solution. Much simpler than I expected. I was overthinking it as usual.
To calculate the sum of all rows other than the current row, subtract the current row sum from the TOTAL sum.
So for my question as example:
(SUM(TOTAL Numerator) - SUM(Numerator)) / (SUM(TOTAL Denominator) - SUM() Denominator)
This will give the aggregated compliance rate of all employees other than the current row employee.