be up to

But by refusing to hammer opinions into his writing, Mr Mo forces readers to look more carefully at his characters. With “Pow!”, it is not unreasonable to surmise that he despairs at the state of his society, but only as so many of us in other countries despair at the state of ours. Mr Link’s criticism, that Mr Mo stops short of indicting those who are truly responsible for how China’s society has turned out, seeks to engage him in a conversation that he is simply not having. As with a piece of art titled “untitled”, it is entirely up to the reader to take from “Pow!” what he will.

This phrase appears in the last sentence. could you tell me what it means?