This will not hurt the LR
in any way. I have been doing this for years on both of my tanks and they are not harmed.
Corals, now that would depend on what type. Like Zoomaster says in the wild this happens daily.
I have buttons, zoos and a galaxia that get exposed on my reef when I do a monthly WC
and they are out for maybe 20 min and it has never hurt them.
Remember that LR
is shipped out of water and even after being out of water for days it is still live. Granted after days there is some die off but for a short term it will be fine.