Please do not lock Jobs to the Weapon Class that unlocks them.

[Nuru]

While likely correct, I don't know that we have enough information to rule this possibility out.

Does the fact that Matsui said that "Jobs are not Advanced Classes" mean anything then?

And besides, even if you are a Monk, you are still using a Hand-to-hand weapon which also means you're a Pugilist. lol So that already explains that Jobs are not replacements.