Read it again. You totally MISUNDERSTOOD.
NU can have one million parking spots. That is NOT what matters.
The city officer used the number 6,800 to VERIFY COMPLIANCE with the parking regulation, because according to the official project documents the expected number of attendees is 6,800. If there was a SRO area that would hold, say 1000 additional attendees, then he would have used 6,800+1,000=7,800 to verify that there were enough parking spaces (780 in this example).
So why does it say "No capacity beyond 9,870" on the summary page (p.21) and "Proposed: 9,870 max capacity" on p. 26?
If anything the document reads to me like there actually could be room for more than 9,870 in the building, but the max capacity will be constrained by the number of parking spots.