Are you saying peds should wear helmets or just using that as an argument as peds would benefit wearing helmets as much as cyclists or even more so?
The use of emotive blackmail and the "proof" that this test constitutes has no place in the debate on helmets, it is the worst form of scaremongering.
Helmet use should be discussed using facts and these then lead to the individual to make an informed decision. If you feel you need to wear one, then do, if you feel that your personal asessment is that you don't need one then don't.
Someone telling you that unless you do there are going to be painful consequences is not a helpful or constructive contribution to your decision
The pedestrian analogy works as it shows simply how absurd and unfounded these claims are
But to answer your question...
1. Helmets are designed to act in low speed impacts and are more suited to pedestrian use than cyclist
2. There are more head injury admissions from falls on stairs than cyclists, and overall pedestrians feature far more highly in head injury statistics.
3. The "proof" put forward with the wall test and claimed as valid is equally "valid" for proving pedestrians need helmets.
4. If you are going to spout a "wear a helmet or suffer pain" argument you really have to justify why you are limiting this theory to cyclists
Overall though it is simply a tool to show the weakness and poor science of many pro-helmet myths and claims