I really dunno, I just wandered in off of /v/all , 'cause of the titlegore.

To intentionally fall on one's sword (such that it impales them) is a suicide euphemism. http://www.phrases.org.uk/meanings/133350.html

It could be a well-intentioned warning that she(Rosie) has been down that road, and was threatened. it could be a threat-veiled-as-a-warning in which Rosie is herself a part of the corruption and is trying to intimidate this blogger.

Then that leaves me curious what the tone of the conversation was, whether it was a friendly warning or a veiled threat...

Your title is an absolute trainwreck.

Which of these occurred?

Rosie O'Donnell warned a blogger not to fall on their sword, and the blogger spoke to you?

OR

Rosie O'Donnell recieved warnings not to fall on her own sword, told a blogger, and the blogger told you?

or was it something else entirely that you failed to clearly articulate?

If there is one thing Rosie knows, its pizza.

Rosie has been using her money and influence to fight this kind of thing for quite awhile. Her response to pizzagate was "It's great that we have so many people looking at this problem now, it's been a problem for such a long time". That she's a public figure who can get people to pay attention, yes, that'd make her a target for intimidation. No surprises there.