I would stress out too much about that q, I doubt much if any weight is put on it, but why not just play it safe and waive your rights?
If your boss was going to show you it anyway, who cares? And if he/she wasn't, then would you want to go behind their back and get a copy from your school? Finally, you probably wouldn't care what it said unless you were denied admission, at which point its kind of pointless anyway.
That's what is so confusing, why would a school care if I read the LOR or not? There shouldn't be anything in there I don't know already anyway. There's just something I don't like about "waiving" my rights to anything.
Actually, that's why they ask for this waiver, because if you know what your recommender is writing about, he or she may not be actually doing the right thing - Ok I know about the "border line" here. So the thing is: if you waive your recommender supposedly will right what she or he "really" thinks...
Rhyme´s guide to interviewing