I read all of that manifesto, and I'm not really convinced. Some of the things he says are definitely true (e.g. that you are not being more efficient when you try to pull the pedal upward), but there are also rather many unsubstantiated claims (e.g. about float and needing lateral ankle rotation to take stress off the knees). Overall I agree with you that a platform pedalist will be a more complete rider and will train additional core muscles and joint stabilizing muscle ends, but this is the same as acknowledging that it requires more effort and energy to ride that way. For me personally, I prioritize comfort and that means clipless pedals. If you prioritize speed, you should also go clipless. If you prioritize safety, athleticism or technique, you should probably be using platform pedals. And shin guards