From a metagaming perspective, The antimagic trick should be allowed to work against mooks and random encounters, but any BBEG/ important smart caster types should be allowed to rcognized typical PC tactics, and have set plans/contengents against said cheezery.
If that isn't obvious, then yer welcome. Otherwise, nothing wron with it. expensive trick to use against chumps tho.
IF he has used the anti magic beat down trick less than twice in the course of his entire career, I'd say he can still catch highly intelligent oposition off guard... but if it's a routine, I'd think he'd earn a reputation for being the anitmagic sword guy. PC's love/hate it when they earn reps in your world.
I've got some PC"s in the Gestalt game getting dangerously close to that same situation.