Apple's claims of infringement sound legitimate, but this phrase seems over the top to me:
Corellium makes no effort whatsoever to confine use of its product to good-faith research and testing of iOS.
Suppose for a minute that they hadn't violated Apple's IP and were instead offering this service with a license from Apple. If a product or service like this can be used for both proper and improper or illegal purposes, must the company make efforts to "confine the use" to proper purposes, and be legally liable or subject to lawsuits if they do not?
If Apple made it part of their license agreement, then yes. Then Apple could pull the license and sue them anyway. They would have had to get a license AND not get Apple to put conditions on it -- which probably wouldn't have happened -- hence they didn't bother trying to get a license.