Replace "threshold" with "critical point." I'm using this terminology because EY himself uses it to frame his arguments. See Cascades, Cycles, Insight, where Eliezer draws an analogy between a fission reaction going critical and an AI FOOMing.

It thinks way faster than a human, remembers more, can make complex plans ... but is it smarter than a human?

This seems to be tangential, but I'm gonna say no, as long as we assume that the rat brain doesn't spontaneously acquire language or human-level abstract reasoning skills.