I know the rule came from Travis at Indie Board & Games directly but I still think he should be able to lead. It's not thematic if he can't, don't you think? I mean, if you were in a burning building and a dog wearing a FD vest came up to you and barked for you to follow, wouldn't you? It'd be safer than sitting in a burning building. To not make the dog so over powered, maybe the dog can lead for 3 AP because he has to wait for the POI.
We were guessing about this rule in a game last night. We concluded thematically that since a regular firefighter can lead for half cost (1 instead of 2), the dog should also lead for half cost (2 instead of 4).
I agree that thematically it makes little sense for a dog to drag a victim that is treated, unless treatment just means they can walk with assistance from a firefighter (maybe one arm around a shoulder?), but the dog is too short to help hold them up.
Or you could roll to "determine cynophobia" - a treated dog lover will follow the rescue dog but someone with fear won't go willingly, and has to be dragged out kicking and screaming.