It seems he was in the middle of uncovering some damaging info on pinkcoin. His last few posts reviled some names and immediately he was asked to contract them in private, looks like to pay him off or they could have been planning his disappearance.

pinkcoin's response to PG releasing some of the names:
tweet me @cryptocayce so that I may share some Pinkcoin love with you as well as a lottery ticket or two.

https://bitcointalk.org/index.php?topic=624017.msg7367716#msg7367716