Think I would believe the results of an MRI scanner Garp as tangible, physical proof of the depth of a marinade penetration - an ingenious idea by the 'off the wall' inquisitive Heston to establish just why Indian cooks insist on using yogurt - rather than your cynical rejection. Take the time to find and watch the programme - here is a snippet -
https://www.youtube.com/watch?v=GDQQKgnh2YI.The comment wasn't made about marinade tenderising as you put it - it was about the depth of penetration of the marinades spices / flavours.
As for your comment
'If this is Ghoulie and Phil's idea of a 'proof' or even of a scientific experiment, they really need to get out into industry ' - as a chemist and a recognised expert in my field with 50 years experience, I hardly need your lame rejection of another expert in his field - Heston - to make your dismissal stand up to scrutiny. Don't expose your apparent ignorance any further with more protests of the inadequacy of Hestons findings / work.