I'm sure this has already been addressed but the "infinite" stops as soon as the first token is made. The Meathook Massacre ONLY gives -X/-X when it enters the battlefield. It only affects the creatures that were on the board at the time of the Massacre. Anything created afterwards will have survived the Massacre.
Yes, it has been addressed, and you're looking at it wrong. Chatterfang doesn't care about Massacre's -X/-X ability. You can play Massacre first, you can play it for X=0. The second ability is what goes infinite with Chatterfang and Pitiless Plunderer.
Chatterfang's activated ability costs 1 mana and 1 Squirrel. And when that squirrel dies, Plunderer gives you a Treasure, which makes Chatterfang give you another squirrel, which incidentally is exactly the cost to activate Chatterfang again. Just keep activating it over and over, and each time, Massacre throws another trigger on the stack that says "each opponent loses 1 life." Once you have enough triggers to kill all your opponents, stop activating and let the stack resolve. You win.
So, it's not really that it goes infinite with Chatterfang and a Plunderer, more that there is an established infinite loop there already. What is important unlike Blood Artist, and Zulaport Cutthroat is that this can't be targeted with creature removal and unlike Bastion of Remembrance it has mana value 2.
Other than the fact that the whole thing is fairly mana intensive it might be worth thinking about. (3 for Chatterfang, 4 for the Plunderer, 2 for the Massacre and at least 2 more to create the first squirrel and kick off the chain).
So, it's not really that it goes infinite with Chatterfang and a Plunderer, more that there is an established infinite loop there already. What is important unlike Blood Artist, and Zulaport Cutthroat is that this can't be targeted with creature removal and unlike Bastion of Remembrance it has mana value 2.
Other than the fact that the whole thing is fairly mana intensive it might be worth thinking about. (3 for Chatterfang, 4 for the Plunderer, 2 for the Massacre and at least 2 more to create the first squirrel and kick off the chain).