I too have to ask why this is "trivially false". We hardly have even anecdotal references to people who never heard language until after five (except for stories about children raised by wolves and couldn't learn to speak - not exactly stories we can trust).

Of course that's goes the other way too - which studies are Dr. Germiller referencing? But again - if it was "trivially false" this would mean that it's something generally known because it's observable. And it isn't, as far as I'm aware.