Let Stealthing be the proposition p. If p is the case and ¬p the case, then the negation of ¬(p ∧ ¬p) is unsatisfiable. QED there is a dude sleeping in that v

Let Stealthing be the proposition p. If p is the case and ¬p the case, then the negation of ¬(p ∧ ¬p) is unsatisfiable. QED there is a dude sleeping in that van for whom Stealthing is the case, and an observer outside the van for whom it is not the case; for all values of dude, van, and observer.