If he's training submission grappling with experienced people the conditioning will take care of itself.
Gosh, I wish this were true! I can verify, after years of competitive grappling at high (and sometimes not so high ;-) ) levels, that it's just not enough.
Don't get me wrong, by normal standards it's a great workout. But it's not enough on its own to put you over the top in terms of conditioning as a competitive athlete.
"In the world of martial arts, respect is often a given. In the real world, it must be earned."
"A stupid man's report of what a clever man says is never accurate because he unconsciously translates what he hears into something he can understand. "--Bertrand Russell
"Liberals - Cosmopolitan critics, men who are the friends of every country save their own. "--Benjamin Disraeli
"A conservative government is an organised hypocrisy."--Benjamin Disraeli