I think we need only reflect on our own likely response to any conceivable attempt by a previous civilisation to so forewarn us, to realise the futility of our attempting likewise.
I think that's exactly the mindset that the Sandia National Labs panel adopted: how would we react to any conceivable attempt to warn us away from such a site? What wouldn't work on us, why, and how could we improve that? The article summarizes their conclusions.
Well, we looked at those gigantic pyramids, translated the hieroglyphs in some places to mean that a dangerous curse would afflict anyone who entered, and then went in to explore / loot the places.
So... yeah. That's the level of being willing to ignore warnings that we have to prepare for.
This whole discussion reminds of the novel A Canticle for Leibowitz. i.e., a society arising in the centuries after a nuclear war failing to learn from their ancestors' mistakes.
