11.1 Competitors must make sure that they clearly show that all the required controls have been visited.
11.2 A competitor with a missing or unidentifiable punch will be disqualified unless it can be established with certainty that the missing or unidentifiable punch is not the competitor’s fault.
The finish isn't a control, so the above rule doesn't cover it. I couldn't find anything else that would relate to this.
Recording an athletes finishing time used to be the organiser's responsibility, then with the introduction of electronic punching a it became the athletes responsibility.
WRE guidelines do suggest that an independent timing and video recording should be used at the finish. Was that the case today?