Indeed, besides pushing a new bitstream he also implemented difficulty >1 support, wow!
But why on earth does this warrant a breaking protocol change AT ALL? (Not to even mention that there was no prior notice.)
Well, maybe the old bitstream contained some critical flaw in the signcryption code that was fixed in the new one? I can't think of a different (rational) explanation. But OTOH it wouldn't be the first time for ET to act in a completely irrational way.