IMO he's wrong about at least the importance of it, you can point to many tasks that are clearly not hard coded because they are recent inventions yet are difficult for a general AI (with zero task specific architecture) to perform, e.g. driving, playing jazz piano, playing any video game, doing advanced mathematics. Either language is much harder than all of these things (I think that's wrong) or all of these things require language capacity (in which case it's just another form of 'language = thought').