I am not sure what you are "disegreeing" with. He was asking about prerequisites. Do you think you need to know anything besides Linear Algebra to understand basic collision detection techniques? Then he is ready to learn. If there are more advanced techniques that require more knowledge, this may motivate him to learn those things. Or perhaps he'll get a flavor for the subject and decide that he doesn't need to understand every single technique out there.

To the OP: Don't allow Krohm's ominous list of techniques discourage you. You should learn some basic techniques to get you going (e.g., how to detect if two shapes of certain types intersect (segment-triangle, triangle-triangle, sphere-sphere...) and SAT for basic polyhedral shapes) and then you'll be in a position to learn pretty much anything you need. I wouldn't worry too much about prerequisites. Learn as you have to.