Meaning is not a side-effect of suffering. It's a side effect of correlations between subsets of reality, like those necessary to drive perception and rationality.
"If there is suffering, and none of it matters, then nothing means anything" does not seem to imply "if there is no suffering, nothing matters".
Their claim does not seem to imply that all meaning eventually derives from suffering. Only that either some suffering matters, or nothing matters.
It also doesn't seem to imply that if there was no suffering that the statement would still apply?
I think?
This statement means that the 'mattering' (meaning) of anything else is contingent upon the existence of meaningful suffering. So if there were no suffering, nothing else could matter.
If there exist some X, and it was true that either some X Y, or nothing Y, that would not imply that if it were the case that there are no X, that nothing Y.
If it is true that (H & J) -> K, and it is true that H, then it is true that J -> K.
Let H be "there is some suffering", let J be "something means something/matters", and K be "some suffering matters/ means something".
J -> K is equivalent to K or not J.
If one believes that "if there is some suffering, and there is something that matters, then some suffering matters", and one also believes that there is some suffering, one could then conclude that "either some suffering means something, or nothing does". This does not mean that one could conclude that "if there WERE no suffering, nothing would mean anything". Rather, one would only conclude that "if there IS no suffering, nothing means anything", but that is only because one already believes that there is some suffering. One could, under the beliefs above, reach the conclusion that "if there is no suffering, <insert anything here>" by the principle of explosion.
But like I said, it is the exchange of information that gives things meaning (that's what minds do,) and the only way to actually make nothing matter is to destroy all information-processing systems.