I've been the judge director for Seattle region several times, but it's been a couple years since I did it last. Even if they post the results right away, I don't think its an advantage, and here's why:
The styles that need to be rebrewed need to be rebrewed. Period. I've seen a LOT of 30-34 point 2nd round beers because the entrant didn't rebrew. We can tell. Trust me.
The entrants are only entering a max of 6 beers. That is a lot but isn't so much that it's impossible. The rebrew dates for all entries should be set ahead of time, which may or may not be after the notification date, depending on the styles. The worst thing that can happen if you rebrew without knowing if you advanced is that you won't have to mail them in. You'll have a fresh batch of a style that is best served fresh anyways. You could send it in to another comp, or bring it to club night, or bring it to your friend's kid's graduation party, or drink it yourself, or a hundred other things.
Oh, and don't expect a lot of great actionable feedback that you could apply to your advancing beer. You'll get better feedback at local comps and from the guys in your home brew club. At NHC, with the check box score sheets, we are really only documenting what is there and not offering a ton of feedback. Its sheet is too brief and there are too many beers to judge to provide really full, expressive feedback.
What you're missing about the rebrewing isn't that the beer needs to be rebrewed to score well in the second time. I think a lot of entrants get that (not all lol.) The issue is people don't want to rebrew the same style they just had if it isn't necessary... That's where you see people that got results late and didn't rebrew even if they wanted to.
I think the fairest option would be to post all results at the same time. I don't think I have much of an issue with results being posted on a first come first serve though as long as the dates of the 1st round judging sites are posted ahead of registration... Which I think they were the past couple of years.