The strong AI problem is much easier to solve than the problem of motivating an AI to respect liberty. For instance, the first one can be brute forced (eg AIXItl with vast resources), the second one can't.

I don't believe that strong AI is going to be as simple to brute force as a lot of LessWrongers believe, personally, but if you can brute force strong AI then you can just get it to run a neuron-by-neuron simulation of the brain of a reasonably intelligent first year philosophy student who understands the concept of liberty and tell the AI not to take actions which the simulated brain thinks offend against liberty.

That is assuming that in this hypothetical future scenario where we have a strong AI we are capable of programming that strong AI to do any one thing instead of another, but if we cannot do that then the entire discussion seems to me to be moot.