The exclusion is "9 Any Claim arising from using a two-wheeled motor vehicle as a driver or passenger if You are not wearing a crash helmet where the engine size of the two-wheeled motor vehicle exceeds 100cc"
So by my reading of that, to be excluded from cover I have to be riding without a helmet AND have over 100cc. So as long as wearing a helmet, even borrowing a road licensed bike off Valentino Rossi should be covered.