The chap you were talking to has a very sloppy formulation, to be sure; but the question is quite interesting.
He might just be an idiot(hard to say one way or the other from what little I know of him) or he may have been incautious about expressing an at least defensible idea about the world. For example: One could say that one can only know truths as relative to other truths. This is actually fairly plausible: Things like mathematics are quite certainly true; but they depend on axioms and rules of logic, which they cannot prove. This is why you get things like Euclidian and Non-Euclidian geometry both being true, while contradiction one another.
One might make the same argument about any system of knowledge, that you need to assume some sort of premises(after all, how could you prove something without anything to prove it from or by) but that given those premises you can make absolute statements about what they mean. This would mean that there are no "absolute" truths; but it doesn't imply that ghastly, squishy, sophmore-in-highschool-who-has-just-read-Philosophy-For-Dummies version of "relativism" where you just say "There is no absolute truth, some things are true for me, others are true for you...lolol I am t37 deep.".