He's not saying it can't be statically typed. He's saying it's type specificity is very coarse grained. A stream of bytes has a well defined static type. But it

He's not saying it can't be statically typed. He's saying it's type specificity is very coarse grained. A stream of bytes has a well defined static type. But it's a very coarse grained one. As a method of communication a stream of bytes can express or contain almost anything. It's narrow in that it's type does not prevent any specific compositions or expressions of a wide range of things. Similarly plaintext is an example not a requirement. Like any analogy it breaks down at the extremes but that doesn't mean the analogy is a bad one.