My first reaction was, "Whoah, cool. All your base are belong to us." But after a moment's thought, this might not actually be such a great idea. Given the communication skills of some players (especially in the battlegrounds), I'm not seeing this as a litmus test of what in-game speech can pass for spoken by real people. While I'm pretty sure the AI won't communicate like a roleplayer, the AI could probably get by with a series of "lol" and "kek" typed out in rapid succession.
This isn't the first time we've heard about the military using WoW (or WoW-like systems) for training purposes, which is the nominal purpose of this new AI research. Maybe it won't be too long before we're logging in to have a Gnome Rogue named Joshua quietly whisper us, "Shall we play a game?"