Alma 50:32

Now behold, the people which were in the land Bountiful, or rather Moroni, feared that they would hearken to the words of Morianton, and unite with his people, and thus he would obtain possession of those parts of the land, which would lay a foundation for serious consequences among the people of Nephi; yea, which consequences would lead to the overthrow of their liberty;

Moroni was afraid that the people in the land Bountiful would listen to Morianton. They might join him. Then he would control parts of the land. This would cause big problems for the Nephites. It could lead to them losing their freedom.

Moroni worried that once Morianton’s people reached the land Bountiful, they might convince others to join them. If Morianton gained control of those northern lands, it could have serious consequences for the Nephites. It could cost them their freedom.