The Rangers confide in Sean that their main concern with returning to their posts is because they fear The Rangers may get involved in a active conflict with another paramilitary soon. They do not want to be caught away from home if war breaks out.

They're fine with Sean, his allies, and his operations. But the threat of a war cannot be ignored.

The potential enemy they may come into conflict with is a rival semi-army calling themselves The Troubleshooters.
The Rangers have been hostile to them ever since the gang managed to take over an Old World fortified building as a base - the Rangers wanted that place for themselves, since it's both very close to their territory's most "sensitive" parts and it probably had an Old World stuff stash.

Currently, negotiations are ongoing, no actual violence between the two factions have happened yet. But the gossip says that The Troubleshooters are growing hostile, confident in that they can simply fight The Rangers off.