I don't think the rigorous definition of the field is the important bit, rather the kind of area one has expertise in. These days people will develop expertise with a set of "tools" and then apply them to whatever area they'd likem. We get feminist critiques, Focauldian critiques, deconstructive arguments, LGBT critiques, etc., that take on political and social issues in a very slanted manner because they analyze the issue in terms of a this framework. Instead of being experts on feminism, for example, we get experts on everything from a feminist perspective. It's good to have this perspective, the problem is that the perspective is overwhelming. The point is to analyze the issue from this perspective, but we've lost a focus on the relative importance of this perspective and the issues it raises. Moreover, sometimes the issue itself is obscured because it is contorted to be analyzable by this framework.

I will say, the problem he delineates doesn't seem to plague all of the humanities, only certain areas. Analytic philosophy departments and history departments seem to not suffer from the same problems.