This preprint reframes wormhole traversability as a transient, response-limited accessibility phase governed by null congruence evolution. Using a Raychaudhuri-based formulation with bounded defocusing, we derive an intrinsic minimum actuation duration set by the focusing scale and show that near-horizon redshift induces a diverging external coordinate-time “dilation tax.” We include a toy numerical phase scan illustrating a threshold curve separating sealed and open regimes. Keywords: wormholes; Raychaudhuri equation; null congruences; traversability; control-limited dynamics; semiclassical gravity; redshift