You are not allowed to depend on the service disconnect enclosure to be the only connection between ground and neutral. I have shot down many where the GEC was terminated to a lug that was screwed to the can and the neutral was bonded to the can with a green screw. Not acceptable. Don't have the Code reference, though. Sorry.
I think there is more to it then just 250.24(A)(1). That section does tell us where we are permitted to connect the GEC.
200.2(B) says: The continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.
This means the grounded conductor (neutral) can not rely on the enclosure or a raceway or cable sheath to carry current of the grounded conductor. It doesn't mention the GEC, but the fact 250.24(A)(1) doesn't mention the enclosure limits the use of the enclosure for the GEC, but not necessarily for other neutral to ground bonding situations
250.102(A) says: Bonding jumpers shall be of copper or other corrosion-resistant material. A bonding jumper shall be a wire, bus, screw, or similar suitable conductor.
In application of this one we commonly depend on the incoming neutral conductor then a screw that bonds the can at service equipment and from there metal raceways serving as EGC's for downstream circuits.