The debate has always been about whether the vmkernel is itself a derived work of vmklinux or Linux.
Ie, for some definition of independence and separation, how independent are vmklinux and vmkernel, and how separated are they in function and use? Could one simply remove the linux parts and plug in a different unix like kernel?
With two independent work I should be able to put them each on a different computer and have a meaningful result from doing so. Two work can have a cumulative effect when brought together, but independent they need to still be meaningful and working on their own. If I arbitrary separate a program, I can obviously not do so since they will not start, function proper or produce a meaningful effect on their own.
Please refer to the quote from the license I've provided, and belorn's thought experiment here.