You let Kearnen have her way. Mortwake stops faffing once he has a bullet in him. The Furlbrows go down easily enough after that. Unfortunately, you discover upon arriving at Sentinel Hill that your detour to Mortwake has given the Defias kingpin enough time to burn Sentinel Hill and leave for Moonbrook. Having already trusted the goblin this far, you trust him far enough to help Kearnen trail the kingpin, who you bulldoze with haste.
At long last, enough haste.