Well in theory you should not need a button on a big block Mopar. But theoretically bumble bees should not be able to fly either! As stated, the gear should hold the cam in place. The only way the cam could possibly move is if you rotated it backwards. Then it would basically "screw out". In normal operation, regardless of RPM, that cam should not move forward - at all - ever! Now if that bronze gear wears, all bets are off.
As for talking to the guys at KB, how many BB Mopars have they built that aren't running a fuel pump driven off the cam? There's your "button".
Anyhow, despite my thoughts and opinions on this, I run a cam button. Hell, for a couple of bucks, why not ?!?!