Large capital ships such as those used by Anton, Kate, and Morningstar are generally reasonably fast. Unfortunately, not all ships can keep up with them (cough, EI100/M). Missions should probably account for that (eg. When following a capital ship to destroy a station as in the C!Charon mission with Anton, the ship should wait for the player to catch up when they're about to get within range of the station).
Though it is in-character I feel for Anton to yell "Follow me!" then vanish off into the distance leaving the pilgrim behind.
(This also need to account for mods altering the composition of NPCs on missions. For example, the Anaxas mission to attack the Cyclops HQ assumes that all vessels have the same speed an acceleration. If you change the (entirely underlevelled) Ronin/Cs to a mix of other vessels, that assumption fails and ships arrive in a stream rather than a group.)