Why would anybody assist Kirk, who is an evil terrorist in cahoots with another evil terrorist who intends nothing but evil to the innocents on Earth? And the valiant Marcus appeared quite capable of handling the terrorist all by himself, so when he told his underlings (that is, the entire Starfleet) to stand back, they no doubt found nothing to complain or wonder about.
That the warp chase would end at cislunar orbit would appear more Sulu's doing than Marcus'. After all, it better serves the aims of Kirk (warn Earth of Marcus) than Marcus' (stop Kirk and kill Khan so that it all looks legitimate). Quite possibly the Vengeance wasn't all that capable of forcing other ships out of warp after all, although once the prey did drop out of warp, there was little hope of getting those battered warp fields up again.
Timo Saloniemi