I'll first say, the idea in the tweet ( revealing that the rock is fake & hollow, thus the ascension is hollow and fake ) is just wrong and a symptom of forcing something to fit the narrative. The rock is clearly heavy, and not every headshot kills you. or if it did, it's more likely Bong wanted the ending that way, where the son survives, rather than adhering to physics and biology. Here's the evidence
It's clearly heavy, and no one is being fooled by their weight. The more apt way to read this
rock, is a critique of Korean society, thinking that rocks bring good fortune and then later being the tool used to kill and inflict significant violence onto others.
They obviously do, the father talks about how much the salary of the son is going to impact their lives and make everything better. Does this mean the rock has mystical powers? No, I don't know why it's cause and effect for you, the rock was introduced but the tutor was also leaving. The rock didn't make this occur, the tutor went off to wherever (I forget). If you want to believe that the rock had powers, I don't know how one can justify this earnestly.
The family was already ascending without trickery, the tutor propped up the son because he wasn't worried about him banging the youngin'. They had even more success by hiring the daughter, which was trickery but obviously offered a service they thought they needed (and I think a legitimately hilarious point that wealthy people believe mumbo jumbo she spewed to act as if she was a qualified child psychologist).
One cannot ignore the climb that was happening with only the Son being hired, this was significant for the family, the problem was they
got greedy and went too far. The idea of "I don't care about others as long as it benefits
my own", parallels much of
Mother, which again is prominent here. Bong clearly couples these together for a capitalistic society, or at least an asian/korean one, and is his critique of the ascension -- not that it is hollow or premature.
I would argue the film has no interest in depicting a hollow or non-hollow ascension story, and I'm not entirely clear why the film would be viewed this way.
If you think the tweet says this much, then it's directly going against the conclusion of the film, where this short experience is irrelevant to how the Son will rise again and return his father to this world. All while being based off an incorrect interpretation that the rock is hollow that isn't supported in the film.