Interesting, I read it differently. I read it as being internally inconsistent.
From my perspective it says "you need to hand over the plaintext if law enforcement asks for it," which would imply that a master key of some sort needs to exist.
But then it also says that nothing in this act can be construed to require a specific design. But requiring a master key to exist would be requiring a specific design.
The proposed law sounds internally inconsistent to me.