How does the English word "meaningless"
The same as senseless, ill-conceived, or pointless. We use these terms to criticize the perpetrator, not to make light of the deed or the victim.
English is not his primary language, so before we get hung up on professorial level semantics, looking for the intent is a good beginning.
You flunked the intent test recently.
But having them executed at Katyń, gave no hope for any Pole to have any good opinion or relationship with the Kremli
Couldn't say it any better. That crime was the stupidest thing ever in terms of cost vs benefit, if not morality.