Selective availability was defeated a long time ago which is one of the motivations for Clinton formally turning it off in 2000. Also while I'm sure that the US military is fully capable of turning off GPS satellites however they want the efficacy of this is probably limited considering the coverage of GLONASS + EGNOS.
The point of that article is that a main justification for turning off selective availability was that the US could still deny access in certain geographic areas. Selective denial != selective availability.
