Yeah, there's clearly a website error there.
I'd hate to see this thread degenerate into arguments about the two classes, or age limits, or the like. The bottom line is that both classes will introduce skills and concepts that the OP probably hasn't encountered in his training thus far, and mastery of those skills will make anybody, I think, a more comfortable and confident diver.
I am also in strong agreement that, when your diving tells you what you need to know or to be able to do, you go find training to learn that thing. But to some degree, that fails at the lowest levels, because the student may not know the thing is even there to learn. Many divers here in Puget Sound have no idea that there are ways to kick without disturbing the silt on the bottom, because they were trained by people who don't know those things, and they have never seen someone dive without silting. The same goes for being able to back up -- I know quite a few people, in life and on line, who are astonished to find that it's even possible!
It's hard to yearn for what you don't know exists. That's why either diving with DIR or cave trained mentors, or taking the classes which have been mentioned, is something I will continue to recommend to anyone, regardless of their diving goals.