Same happened to me. The rock that the rope is tied to was glowing, but there was no prompt to interact w/ it. I left & fast traveled a few times, aued a couple missions, & when I came back, I had to kill the guys again, & that time, it let me interact w/ the rope & rescue he woodworker.
It's a glitch. If you fight one of those guys near the stump where the rope is tied or you kill one of those guys and their body is too close to the stump, the prompt to pull the guy won't appear on the stump. Reload the mission and try again.