Call me slow, but can someone explain to me what the above post mean?

I think he was talking about "developer privacy safeguards". Basically, there is none.

Since there was no denial we can reasonably assume there are no stringent safeguards against engineers accessing user data.

I believe he is not confirming or denying the allegations. Make of that what you will.

Since this is your alias, I hope you won't mind my curiosity--when did you leave the company, and do you have any thoughts about leaving?

I left late last year because I got a better offer and was fully vested. I suppose I was in a small minority that wasn't drinking the koolaid. The perks were nice, but ultimately I felt I wanted more stimulation than working on a social network, and didn't like some of the features that were being pushed (face recognition on photos, etc.) I'm grateful for the opportunity, and can't say much else.