Have you actually been exposed to any high-level contemporary philosophical research? While it is true that many philosophers do care about the history of ideas, this is quite often done in order to treat various philosophical questions systematically (for many philosophers, it's all about the questions, not about any 'philosophy' that needs to be studied). Besides, for many philosophers there is also some interest to integrate their work with the work of researchers in many other disciplines. If you work in philosophy of language, it would be ridiculous not to try to acquire some working knowledge of linguistics and cognitive science. If you work in epistemology (aka the theory of knowledge), you have to have some knowledge of cognitive science, game theory, computer science, psychology, evolutionary theory, and so on, just to know what other philosophers might be discussing.
GP's claim could be parsed in many different ways (what is 'understanding'? what is 'the structure of knowledge'?), and the suggestion that whatever that is is 'predominantly done' in computer science betrays some ignorance (or perhaps some willing obtuseness) about the alternatives. That you think that their claim was meaningless says more about you than about the claim. Why, instead of disagreeing with GP immediately, don't you ask them what they mean? You know, engage with a philosophical thought?