Not quite. I wrote: "Isn't Butler mourning 'the death of Marx'?" See, sometimes quotation marks make a crucial difference. To me, Marx has left us a living legacy, and we may still inherit the earth (hopefully in a decent working order). Nothing is guaranteed, of course, but I say, that's what makes it interesting and worth trying.
To Butler, and alas also to Foucault (much as I like his writing, which he called 'an invitation to an experience'), Marx has become 'Marx,' transformed through the mourning of '68. Post-structuralism is a dirge--melancholic and self-reflexive, seducing us to think of a temporary defeat as Death. (Music: 'Adagietto' from Mahler's Symphony No. 5. Ambience: The Vienna of Freud. Digression: Have you seen Daniel Schmid's _La Paloma_ by any chance? The film embodies the Adorno fragment you sent us: "Decadence is the nerve centre at which the dialectic of progress becomes ... bodily appropriated by consciousness.")
good mourning,
Yoshie