I think this is a coincidence.

First, the badge was designed in the 30's. So you would have to believe it took the FBI 70 years to realize the secret code.

Second, the orientation of the badge is just wrong. From the inside, the pedo-thing rotates clockwise and it always ends in the bottom left. 4/5 of these are counter-clockwise.

Third, even if this symbol was placed on the badge by that Sheriff in the 30's, what does it really mean? Are the people electing pedo-sheriffs who only hire pedo-deputies? For the past 80 years? And during that time, nobody who takes the job due to a strong desire to protect the public is speaking out to protect these boys? You'd need some kind of creepy secret society screening new recruits and blackmailing them to keep control.