Even if, the uncontaminated soap is used to wash the hands AFTER touching the dispensor. This is a BS study.
The soap itself is contaminated.
Yes it is. True soap does not become contaminated. What becomes contaminated is the water that was used to dilute a bulk concentrated “soap” product which most likely is not 100% true soap at all. If the water becomes contaminated what it dilutes will obviously also get contaminated. It is the water that is the medium for bacteria not soap.
Also it is the dispenser knob that gets contaminated.