You are not totally correct.
Yes, this is not uncommon in large road races and it is almost impossible to call back a false start. I have seen it done in Championship events were there only 50-100 runners.
1. We need to be very careful that we not only protect the integrity of the time of a "new" record setter but that we also protect the performance of the athlete holding the record.
2. Passive transponders have a varying degree of accuracy and can be off as much as 0.5 seconds or higher. (Active transponders are much more accurate - within .05 as compared to FAT). Road race times are rounded up to the next highest seconds. Add this to the degree of accuracy with transponder timing and the official time could be off as much as 2 seconds.
Also, the IAAF does not recognize net times for records.
3. So the million dollar (Euro) question: what if Kipsang broke the WR by one second?
I have always told my Official timers to start their watches at the break of the first runner.