There are also Russian and ESA mission controls. Normally it seems they do more science support missions than supporting the facility itself, though Russia of c

There are also Russian and ESA mission controls. Normally it seems they do more science support missions than supporting the facility itself, though Russia of course runs support for Soyuz and Progress docking, but if something truly disastrous were to happen to JSC those mission supports could be transferred to another location. That comment is more 'this is how we have the security setup and for a temporary situation like Harvey it's not worth changing everything when we have an alternative plan' than 'there is absolutely no other way to control the station than physically logging in from JSC.' That's pretty clear given that their primary backup site is just a hotel.