How do we know this "propensity for language" isn't an emergent property that is a function of neuron count past a certain point?

"We can probably raise IQ into the low or mid 200s with genetic engineering."

So you don't think 300 to 900 IQ humans are possible? You think 250 is the max of a human?

Speed of thinking isn't the only component of g-factor, it's also memory, the size of the recall-able knowledge space, and how many variables you could juggle in your head at once which imo could keep on getting larger if brains and bodies could also keep getting bigger. Do non-human brains think at a slower rate than bonobos and chimps? Young non-human primates and other animals have pretty fast reaction times. The reason they have lower IQs than humans can be explained entirely by neuron count. Human intelligence is just primate brains scaled up with more neurons. Gorillas and orangutans have brain sizes 1/3 as big as humans. Human brains have all the speed constraints as gorillas obviously. Knowledge and working memory is more important than speed.  A 500 IQ human could outsource strict numerical calculation to silicon calculators