Thanks, I don't have access to the commentary, so that seems helpful. I guess I wonder what the point of Exception 5 would be if it did not include spaces on levels other than the level of exit discharge. By this I mean Table 1015.1 is essentially the same as Table 1021.2 (regarding the first floor). In order to satisfy 1021.1 (5) you need to comply with the entire Section 1015.1 including CPOT and travel distance, so it is in a sense more restrictive than 1021.2. In other words, it seems that 1021.2 already would allow single exits for those situations you describe (spaces on the level of exit discharge exiting directly to the exterior, that also comply with Section 1015.1). It doesn't seem like an exception to anything in that case.
I agree, though, that the commentary suggests reading it in the way that you are.