But you have to grip this bit of moulded plastic equally as firmly as you have to grip your pole. Otherwise it'll fall out of your hand.
Sorry mate, why don't you just say 'Look I've created an alternative method for holding your pole, it's no better than normal, but it's not quite the same. You know, change is as good as a rest. It feels different but isn't any better'.
Lend some credibility to your offerings.
Rather than just saying it won't make a difference, I tried it. It does make a difference.
Try this thought experiment before saying "you have to grasp it as firmly as your pole" without evidence.
Imagine holding a pole vertically. You have to grip it to stop it slipping out of your hand. Now imagine that it had a firmly fixed lug sticking out of the side. In theory, you could balance it on top of your hand without even holding the pole and the pole wouldn't slip downwards. The weight of the pole would be resting on your hand rather than in your grip.
Now, the way it works out in practice is that the lug sits between your fingers rather than on top of the hand but the reduction in grip needed is very significant indeed.
It's clear that you've already decided that it can't work but if you take that preconception away, you just might see that there could be some truth in it.
Vin