From Alma's standpoint, this was the worst possible situation. Certainly the priests of Noah could no longer be accounted as his friends, and there are certainly no enemies as intense as those who were once comrades in the same cause.
Geography: The traveling from the location where the Amulonites were found to the land of Helam had to be on one of the more west-east travels of the Lamanites. Once again the Lamanites would not have gone north, and had they headed directly south, they surely would have missed Helam. Thus they would have been in one of the detours through passes that by happenstance led them to the valley in which Helam had been erected.