Try contacting both. If one doesn't feel up to it, or thinks that the other (or someone entirely different) should delegate, they'll tell you. I know Josh is super friendly, and I'm sure David is too, so don't worry. The sooner you contact them, the sooner you can figure out the logistics of a competition, and whether you should host one.
I know that there have been a few competitions in saint louis before, but there haven't been any in a while, so I'm sure the cubers there would enjoy another competition.