There's so much variance in the game that it would be hard to know how good the AI really is. If they're doing 120K hands heads-up, they'd need to play far more in a full table. Getting that many pros to play that many hands would be difficult.
And what's wrong with heads-up, anyway? It's not as popular as multiway, but it's a fascinating game. In a full table game, you usually only end up playing 20-25% of your hands. Heads up you play 90%+. You end up in leveling wars with your opponent more often, too ("he knows that I know that he knows I usually wouldn't play a premium pair this way").
Maybe you are right, but in Poker championships you see many of the same names in the top from one year to the next, right? (I could be wrong about this)
That could suggest the variance is manageable.
I'd like to see more players because we have seen so many two-player AI contests before (chess, go). It would for example be interesting to see MCTS in this setting.
The variance is manageable if you play enough hands. This is one reason why a lot of pros prefer to play online - by playing many tables at once, you get more hands in and can better overcome the variance.
As for tournaments, the variance is even greater, since it is closer to all or nothing. To mitigate this, pros "buy a piece" of each other. Or swap equity. If either wins they pay the other a percentage. If you do this with enough other pros, you even out your swings...
I don't know if you've actually played poker, but heads up you still probably play only 20-30% of your hands (unless it's a tournament at least). A lot of full table games you can play less than 10% of your hands (just my estimation. A pro can probably tell you better numbers).
If each player follows your strategy, 40-60% of hands are won by nobody.
Playing 10% of your hands is very tight if you're up against other good players. At a loose table it might be very profitable though, especially if the other players aren't paying attention to how tight you are, and therefore don't give you enough credit for having a strong hand when you do play. That kind of table is pretty common at low limits.
And what's wrong with heads-up, anyway? It's not as popular as multiway, but it's a fascinating game. In a full table game, you usually only end up playing 20-25% of your hands. Heads up you play 90%+. You end up in leveling wars with your opponent more often, too ("he knows that I know that he knows I usually wouldn't play a premium pair this way").