Word of Recall

[The Giant]

Also:

When you have a slam attack that inflicts negative levels, you don't study exotic grappling techniques that are only marginally better than what you can do on your own unless you're paranoid about encountering enemies protected from your natural attack and need a reliable way to immobilize protected spellcasters.

This is player thinking, focusing on utility in an average adventure and not to the whole of Malack's life. He didn't learn grappling techniques as a combat option, he learned grappling techniques so his food wouldn't get away. Draining levels with a slam attack doesn't give a vampire sustenance; grappling and drinking blood does. You can level-drain a person all the way down to dead and you'll still be hungry. So this wasn't a crazy-paranoid defensive technique, it's a hunting aid. If it also had utility in combat, well, bonus.