I think it was a satirical answer, that GC can indeed be used for even hard real time systems (though in this case it is a specific hard real time JVM implementation that has a maximum allowed time to spend on GC). Contrary to what many thinks, hard real time is not about speed, but predictability. And calculating even I don’t know how many missile paths is computationally not too hard, compared to eg. even a computer game.

But to answer your question, there are cases where the JVM is used without GC and it runs for a day, and gets restarted at night. Afaik some bank does it for some form of HFT.