Earlier quoted context omitted.
In the grand scheme of things every one dies and the universes freezes from entropic heat death, so yeah... That said Nihilism isn't necessarily pessimistic. The French Existentialist were basically weak nihilism and Camus was almost celebratory of the lack of meaning of life. "Nothing Means Anything" can be taken as "fuck it burn it all down" OR it can be taken as "there are no unforgivable sins, there is no eternal…
But you just did that exact same thing! a) Do we know for sure that's what happens to the universe? and b) It doesn't matter anyway. "Everybody dies" is only a fact. What does the fact of heat death have to do with the question of meaning? The implication that "nothing means anything" is just as metaphysical an assumption as "everything means something."
b)I am specifically claiming that while "nothing means anything" is the--lie that tells the truth--summation of nihilism it, by it's very nature, doesn't imply a course of action. So it doesn't matter how metaphysical of a claim it is.