[QuercusMax]

I just plain don't understand what they mean by "suicide note" in this case, and it doesn't seem to be explained in the text.

A better analogy would be "Robots.txt is a note saying your backdoor might be unlocked".

[stickfigure]

The meaning is reasonably clear to me: Robots.txt says "Don't archive this data. When the website dies, all the information dies with it." It's a kind of death pact.

[QuercusMax]

That's not a suicide note, though, in any way I understand it.

[stickfigure]

It's the inevitable suicide of the data.

Language gets weird when you anthropomorphize abstract things like "data", but I thought it was clever enough. YMMV.

[QuercusMax]

The suicide of the data listed in robots.txt? How? The whole point of the article is they ignore what you have written in your robots.txt, so they'll archive it regardless of what you say.

[stickfigure]

Correct, they are challenging your written wish for data-suicide.

[chao-]

I also cannot figure out from context what part of this is "suicide".

I don't even think it's a note saying your back door is unlocked? As myself and others shared in a sibling comment thread, we have worked at places that implemented robots.txt in order to prevent bots from getting into nearly-infinite tarpits of links that lead to nearly-identical pages.