"Can't" there was presumably meant as an ethical or moral statement, or as an imperative, not as a description of possibility.
In the same way that "must" can either mean that something is inevitable, or mean that it is imperative.
In the same way that "must" can either mean that something is inevitable, or mean that it is imperative.
It's misleading and it shouldn't be used that way. Can't be used that way, even...