It's not future knowledge since this is an alternate reality. I say, he should spill anything he thinks might let them live a happier, safer life. He should offer up the cure for that disease that was going to kill McCoy ( Xenopolycythemia). He should definitely make sure everyone understands the Pon Farr thing.
In this reality, they may never need that knowledge, but if they do, they'd have it.
Thanks to Ron Salon for the signature banner!