Helaman is well aware of the unstable political situation that has existed in Zarahemla. If Moroni has not sapped the reserves, then they are not forthcoming because one of the rebellious groups has found a way to prevent them. Helaman was well aware of the kingmen who where willing to invite the Lamanites in by refusing to raise arms. Something of the sort could be behind the lack of reinforcements. Helaman’s fears are legitimate.