One of the developers mentioned that it involves bots. If there aren't counter-parties or trading restrictions, then aside from bots, how would you keep the price stable? The increase in Peercoin's price may be partly attributable to the bot owners' need to have a large supply.
Ok, I hadn't heard that the developers actually did mention bots. Interesting.
To me, if their plan is to amass a large supply of PPC and then try to stabilize the price by playing central bank, they're just crazy. It's so blatantly obvious that it wouldn't work - unless when they say "stable price" they don't mean "constant price." Anyway, I don't think they're idiots, so I don't think they're trying to maintain a constant PPC price by playing central bank.
It seems like their plan must be to do something like launch cryptocurrency NuBits, then create some kind of price-stable derivative of NuBits (maybe with some similarities to BitUSD) whose price they control with bots via centralized exchanges. Maybe? In that case, the PPC pump is kind of a red herring; it's just people flailing around trying to figure out how to make money on NuBits before they know what it is.