To be honest with you I would have picked Nate too.
Who in their right mind would want to fight Khabib? Aside from being undefeated in his career, the dude was manhandling RDA.
Ferguson has been active and is a great, big, physical wrestler. Definitely would not pick him.
Then you have Alvarez who has been able to point-wrestle decisions from world class guys with relative ease in Gilbert and Pettis. He's also pretty world famous for being able to take punishment and keep rolling.
All of those are bad options. Khabib is a cartoonishly bad option.
Nate is the only top 10 lightweight who literally doesn't know how to wrestle. He likes to box and his biggest asset is his cardio, which won't be a factor when he's not been in training since December.
If I'm Conor and Zuffa and I just lost the shot at the belt I was promised, I'm asking for the easiest, biggest payday available. Fighting Nate Diaz coming off the couch is exactly that.