This exists without Cdist as well, and has since the original game I believe...
No, vehicle would load everything which have no explicit destination. It is not possible to make single order and force vehicle to stuck on station in case of manual cargodist or if station is fresh (with red marked cargo "to anywhere").
But once link is established, vehicle would sit and not load cargo with fixed destination.
It totally kills cargodist idea, were you get higher station ratings traded for local freight. With this exploit you can get high station ratings plus all traffic at long distance.
Possible fix is to generate randomly small amounts of "cargo to anywhere".
Such fix would be also useful to establish new links, currently it is sometimes hard to attach new destination into existing network.
My experimental openTTD server: 188.8.131.52:3979 non-standard client, now testing: JGRPP http://tiny.pl/ggnch
Projects: Reproducible Map Generation patch
, NewGRFs: Manpower industries, PolTrams, Polroad, 600mm narrow gauge, preindustrial houses, wired, ECS industry extension.