This is not necessarily true - about the bindings/skis anyways.
Skis are completely sealed to the elements. As long as you have no core shot or rail missing, you shouldn't have a problem with water seeping into the core. Also would recommend re-gluing the mount holes just to give a fresh line of protection. That is really you're only vulnerable spot.
As for your bindings, the water should not hurt them. Snow gets deep in the crevices every time you take them to the slopes.
But taking them swimming get's them more wet blah blah blah. True, but bindings are fairly simple.
You have a spring, a bolt, a few metal pins, and then the rest of the housing that is not metal is composite.
The internals are covered in a lithium grease. This will prevent rust from happening. As long as you are sure to thoroughly dry your bindings and even reapply a thin layer of lithium grease, I foresee no prolems arising.
If you are truly concerned, and for an extra line or protocol, I'd recommend having the retention and release checked at a shop after the ramp sesh.
The only thing vulnerable on your set-up, in my opinion, is your boot liner. For that, I would use an old shitty pair.