What Moroni does admit is that it appears that “God ceased to be a God of miracles.” As an unchanging being, how is it that this appears to have changed.
Moroni is clear. It is our fault, not God’s. “And the reason why he ceaseth to do miracles among the children of men is because that they dwindle in unbelief, and depart from the right way, and know not the God in whom they should trust.”