He never gets me anything
With any achievement that has to do with not boarding anything on Halo 2 can be done easily using this method. Guess what? You still get to use the tank, or even the Gauss Warthog. Simply at the end of the mission before you finish it, SAVE AND QUIT, then resume. Finish the mission and you will obtain the achievement. My final checkpoint was in a warthog and I still obtained the achievement.