'Dummy' means 'pacifier' in some places, so 'spitting the dummy' literally refers to the temper tantrum of a baby. Hence, to 'dummy spit' is to throw a massive, immature temper tantrum.

That said, I don't think this is really a justified criticism we have here, pending further details.

Sorry, it's Australian slang, I didn't realise.

Well, those "pending details" don't seem to be stopping the soppy eulogies and reposting of the guy's old blogs, etc, like he just died a tragic death. I felt the need to counterbalance with a healthy dose of scorn.

Let me share my estimated likelihood of the various scenarios:

   0.1% - why is dead and the actions are that of a script
   0.1% - why has been maliciously hacked to an unprecedented degree
  99.8% - why has, in fact, spat the dummy, and thrown all his toys
          right out of the pram

I guess time will tell which turns out to be the case.