Hiding public things on a blockchain is complex. The 7 days is there so folks know who got what. 7 days isn't arbitrary, it's the block proceeding the block that pays the AR.
This is the same as saying it takes 1 confirm from the AR close until AR payment.
Okay, sure. I thought maybe the data could be encrypted or something, but not really a big concern. This sounds fine.
I like this explanation better @williambanks, rather than it sounding like someone is 'gaming the system' (although it may be accurate). @cryptomancer, perhaps the explanation can read:
"ARs must be submitted on or before the 83rd day (7 days before the end of the 90-day period). At the end of the 83rd day, the AR awards are closed and recorded on the blockchain; on the 90th day, the AR awards are distributed and recorded on the next block on the blockchain. In this way, the AR awards can be recorded on a block-chain block preceding the one which includes the actual AR distribution. In other words, awards are recorded on one block (day 83), and the awards distribution are recorded on the next block (day 90). This gives everyone involved a chance to see to whom each award is given."
Of course, @cryptomancer, you may have a better explanation, or something - umm - less wordy :-)