This is some weird way of counting. A system pause plus a GC pause is two pauses. Just because one pause can't be avoided doesn't mean you can introduce more pauses.
Just to be clear, the pause in ZGC is done as an optimisation of thread synchronisation (there's no GC work done in the pause). It's just as easy to do things without anything you would consider a pause, only it's less efficient. Momentarily stopping all program threads is just an efficient way to deliver a message to all threads considering that the OS might have some threads descheduled.
At the end of the day, we care about the latency for some particular thread(s), and truly minimising that at this level requires a realtime kernel (that comes with significant performance disadvantages).
