I'm not questioning it, aside from the daftness of it. I agree with the ruling on a RAW basis, but it's one of those stupid things that crops up from time to time by having monkeys used to type up the handwritten notes provided by the games developers.

However, in regards to "not having charm person if you have charm person, mass";

This spell functions like charm person, except that mass charm person affects a number of creatures whose combined HD do not exceed twice your level, or at least one creature regardless of HD.