Actually it does. Even if Leadership IS a useless feat, how do you skip it if the class is specifically built around the feat? Besides, you can't have two people at level 20. If you're level 20, then the cohort is 18 at max.
Draconic leadership gives you a dragon cohort whose ECL is reduced by 3 for this purpose. Incidentally, dragonwrought kobolds are dragons...
I can't recall offhand if you are allowed to go beyond the table in draconomicon though.
And in your case, even though the class does give you the leadership feat, I say just ignore what it does, save yourself the hassle of calculating its benefits right down to the last 1st lv follower and just throw in whatever npcs you want the party to face.