I have and on the freeway. I run a detroit in the rear. Now the detroit will let a tire go faster than the driven tire but not slower if that makes sense. If you jake the rear up and put it in drive at an idle or so. You can have both of the rear tires chugging along slow and you can kick one of the tires to move faster and it will. The reason that the truck tries to go strait on the corner while under the throttle, is because the locker is applying power to the inside tire. The outside tire might actually be going faster but thats ok because it will not be allowed to go slower.
So on the freeway when your going strait, The tire going flat becomes the ratcheting tire as its Diameter goes down which to the locker, is like going around a corner. The tire that stays full of air drives it harder and it does try to turn you. That is, if you stay on the throttle going down the freeway with a flat tire. If you slowly let off the throttle it does fairly well. When my tire let go, I took my foot off the gas and coasted over to the side.
So I would have to agree with you. If you stayed on the gas while going down the freeway with a flat tire, it would handle bad.