Negligence or on Purpose?

In Hunters in the Snow, was the wrong turn at the end negligent or was it done with a purpose? Tub and Frank had  new sense of bonding. I think it was a conspiracy ending to this story. Frank had seen this new sense of brotherhood and didn't want to share Tub's friendship with Kenny. Tub was also enjoying not being made fun of so he too liked it. The two "forgot" about Kenny in the back, and in my opinion, purposely took a different turn than the one needed for the hospital. My final point, when Tub told Frank that he had left the directions at the table, Frank didn't seem concerned at all. Now I have revealed the Hunters in the Snow conspiracy and found out that Kenny's sure death was no accident.