Sorry but I think you mised the point. Only Elon Musk knows how valuable something or someone is for Elon Musk. You might be able to provide an informed opinion should you have all pertinent details regarding to activities involved, options available and other constraints but otherwise a generic assessment means nothing.
Sure, the ability to have something run by itself freeing up time helps, but is it worth the bump? If you're already doing the work, what exactly are you charging extra for then? Is that the kind of thinking to be encouraged? Is all that worth it considering whatever options there may be?
One thing you can be sure of is that whatever alternate solution there was, it was at least good enough if things were able to run just as smoothly without that assistant.
Of course, you might think Musk was lying and being petty when he said that the position itself was not indispensable. I guess you have your reasons for that.