No, not sarcasm, and I am Eliezer Yudkowsky. I was around on the old Extropians mailing list starting in 1996, and their leadership did not talk like this. Max More (the founder of Extropianism) was a careful thinker then, and I haven't heard anything different about him more recently than that.
"Extropy" is a term that was previously coined by a group of fairly nice people to describe themselves, and so far as I know is being stolen here without permission.
The word "extropy" itself seems to go back several decades before the mailing list, if I'm reading correctly here: https://en.wikipedia.org/wiki/Extropianism. Still, I wouldn't be surprised if many/most of the original mailing list members found this usage a corruption.
"Extropy" is a term that was previously coined by a group of fairly nice people to describe themselves, and so far as I know is being stolen here without permission.