Soul is an oddly subjective concept, Aco, which I`ve never felt the need for/lack of - & in mechanical contrivances. I reckon an eager, willing , spirit is the go.
That 4-strokes, unless pressure boosted chemically &/or by additional pumping are fundamentally lazy, [having a 'siesta' between combustion events] is a disadvantage esp`for the tightly packaged/low mass requirements of racing motorcycles.
If they need a 'special olympics' type dispensation to compete, well...hmmm.