Do we know why Isildur covered for Kemen’s treachery?

That Galadriel training session was really great, and exactly the sort of thing I love to see in things like this. It had a real Princess Bride feel with her commenting on her opponents’ skills while smoothly handling them.

Then did the sons of Tar-Minyatur ride tall and fell and fair
upon the ships of Belegaer with sails blond as their hair
But first they had to lade aboard each single colt and filly
Using some sort of horse pulley harness that all looked rather silly