Look at it this way: imagine you have a server that's totally maxed out (CPU-bound), 24 hours a day. If you add just one more connection to its load, it won't be able to handle it. No matter how long you give it, it'll just fall further and further behind. The requested pages are uncomputable! A faster computer, on the other hand, will keep up just fine, and finish all the computations.

This isn't how computations have been traditionally defined, so that's why it seems so unintuitive. But, he's right nonetheless.