Do you mean to say that only something that approximates human intelligence can initiate an "AI takeoff"? If so, can you summarize your reasons for believing that?

So this is a valid point that betrays a possible unjustified leap in logic on my part. I think the thought process (although honestly I haven't thought about it that much) is something to the effect that any sufficiently powerful optimizer such that it can self-optimize for a substantial take-off is going to have to be able to predict and interact well enough with its environment that it will need to effectively solve the natural language problem and talk to humans (we are after all a major part of its environment until/unless it decides that we are redundant). But the justification for this is to some extent just weak intuition and the known sample of mind-space is very small, so intuitions informed by such experience should be suspect.