That was my thinking as well Jetée, I know I watched the show but can't remember the results, but to me a kick would be the stronger way to strike. Maybe if SF backed up his 'science' we'd know for sure. I guess saying that it's 'scientifically' means we're automatically supposed to fall for it. If the punch is stronger it's because of the smaller impact point, so in that case kick using the heel of your foot.
There's a good discussion about it here, but I haven't had time to glance through it all Hell's Kitchen is on and I'm occupied by the ex Marine who want to go outside with Ramsey.
Punch and Kick Force? - MartialTalk.Com
Yes it's another forum, but it isn't like I'm whoring it or anything but if the mods don't think it should be here, feel free to delete.