There's not any particular reason to trust Woit more than Gross and Witten. But you don't really have to worry about the distinction here. Woit is not advocat

There's not any particular reason to trust Woit more than Gross and Witten. But you don't really have to worry about the distinction here. Woit is not advocating for any of the alternative approaches to quantum gravity. He's aware that they are basically crap. His complaint is that he thinks the string theorists are claiming to have solved the problem.