disqualifying the beneficiaries of that pacesetting i.e. Hill and Jager.
pacing in running or walking events by persons not participating in the event, by competitors lapped or about to be lapped, or by any kind of technical device other than those permitted under Rule 144.3 (i)
If this weren't considered illegal, I doubt they'd have phrased the exception allowing official pacesetters:
because there would be no need to expressly permit official pacesetting if unofficial pacesetting by a race entrant were allowed too.
pace setting by an officially designated person entered in an event for that purpose is permitted, provided such pacesetters start in the event.
This is no small issue! Even where track is a team sport, what matters in individual events is solo performance. Chelimo didn't have teammates to help him, and neither did Lagat. The outcome could well have been different if the rules had been followed. Pacesetting is cheating.