Rulebook 9.6.2. As long as the competitors are informed and there are delegates, it's legal.
Not what I would have guessed, but, clear enough.
I personally dont don't care for the "score keeper" scoring targets. There's time for that when the shooting is over. I'd rather they also do the other RO tasks such as watch for safety violations, penalties, etc. and I've seen too many reshoots given because either the pasters or the RO with the timer thought the score keeper recorded a target when they didn't. As a shooter I like to see my hits.
As a personal preference I am +1 on all of the above. Also, as a selfish matter, it is a lot more fun to watch the action & try to back the r.o. than to be squinting at targets. I'm not sure how much time is really saved by scoring ahead, particularly when hurrying only sets you up to wait a bit longer for the squad ahead of you.