I think what he means is that Auto-wand could be the equivalent of auto-shot for hunters, i.e. we'd be shooting our wand as Destro WHILE we are casting.
And wands being a main-hand weapon just like swords and daggers, Destro would be required to use wands only, no staves, swords or daggers.
I'm sure it's an error in the calculator though... It would be really awkward to cow one of our specs to a single weapon type like that. The only specs that are like this currently in the game are Assassination and Subtlety, but I guess that works for rogues. It definitely wouldn't for any caster.
you can also see it as if we are the only casters that requried a wand, and only dest spec has that. then for me im the only destro lock in my guild maybe wands ill be priority since im the only one that requires using it for dps. they will have the same stats as a 1her, hope they don't make 2h wands, so it might not be so bad