MSOCS
I would not be too sure that the leak was timed for IOC, although it's possible. The test in question took place in January and was first publicized in April, so this could just be slow-boil.
But it does underscore the capabilities that the Marines are getting (or not getting) with IOC, which is another story. This is not a strong IOC, even if the jet performs as advertised, because what a Block 2B can do (fixed target strike against reasonably heavy defenses) has not historically been a big part of the MEU mission. The focus of Marine air has been CAS, undeniably, and the F-35 needs a higher load-out, moving target capability, improved sensors and better comms to start doing that well.
I agree that all these things can be done in time. But the Marine IOC capability would be more accurately called "service test", like we used to do with YF aircraft and the Sovs did with things that had -A reporting names.