Measuring a strange foreign course in a short period of time is often an adventure. You are asked by your IAAF Area Administrator to do the job, and you contact the race people to make your travel plans, which are based on your available time and the race organization’s schedule. You often find that the race people expect miracles which you cannot provide. So you do your best.
It is not at all like measuring a course in your local area. You must work in a hurry and accept that you are not entirely in charge.
In the specific case here we have a measurer making the best of a bad situation. There was an emergency and little time, so he made a choice. In his shoes I could well have made the same choice.
I believe the IAAF Area Administrator must carry some of the responsibility. It is not an attractive prospect to be told that if your measurement is imperfect, you will be cut loose by IAAF and told to either reimburse the race or travel again at your own expense.
In this case we have the measurer using a surrogate rider because he had little choice or time to do otherwise. I see no reason why the surrogate ride, observed by the measurer, should not be accepted as good enough. Certainly it is better than either of the other two choices.
I believe that when the Area Administrator sends a measurer to do a job, he should stand behind him and support him. In this case it seems to me that dumping the responsibility onto the measurer is hard-hearted and not productive. The policy should be to accept the work of the person sent, and issue the IAAF certificate, not to second-guess.