They need no such clause. Why don't you go and form a class action lawsuit against apple - I will sign the petition just so that you will have that .01% of people who gives a damn.
edit: it's the people who claim they have "legal rights" to do whatever they want to a product they purchased...the litigation for this is still ongoing (sony vs geohot)...we will see..
So the ones of you that are ok with this change, and ok with Apple replacing the screws on existing customers' products without consent, you'd all also be perfectly fine if you took your existing car (which has a standard oil plug that the average owner can take out if he/she chooses) to the dealership for an oil change (say you didn't have time to do it yourself this occasion), and got it back with a special drain plug in place that only the dealership has a wrench for? And have done this without your permission?
So you're one of the one's that would be perfectly happy with the scenario I laid out in my above quote regarding your car? Because it's exactly the same thing.
And you're referring to the litigation that is similar to what Apple has already had ruled against them regarding the end user being able to jailbreak their device as they see fit?