I believe his point is that the cheap buildup/teardown of processes is inherently safer and more mature than a monolithic clump of threads in terms of isolating processes and ensuring resource deallocation. The startup time of the VM is a red herring in this case. I too have seen impressive VM uptimes. Almost as good as the OS uptimes I've seen.

Java threads are dead easy as threads go. However, I don't believe that they're going to be a sustainable solution as we move forward. As processor counts keep rising and the focus moves from scaling up to scaling out we need to find more easily understood and debuggable abstractions for dealing with a massively parallel world.