Why is the song Airplanes by B.o.B. explicit and it only has two bad words?

i think its because people who make the song explicit or not either messed up, they made it explicit because of airplanes part 2( which says the "f" Word), or because b.o.b is a rapper so they asume his songs are bad.

EDIT: The people who decide do not mess up. They listen to songs carefully and examine lyrics. The version with Eminem is the only version that is marked explicit, and that's because he swears once in the song.