Hell's Comin' With Me Legend Article III of III: Lacy O'Malley

Oh, you can use the Cheatin’ Resolution of Ancestor’s Reproach in lowball?

I thought since it’s only one sentence (“An Ancestor Spirit enters play at this location and joins your posse”,.with no “If this is a shootout…”), you need to fulfill the whole thing and couldn’t use it if there’s no posse to join?