Some people don't even have the DLC yet, let alone have finished it and started other missions. Ask again in a week
It's faily simple.
1. Have completed For Auld Lang Syne prior to Loensome Road
2. Reach a point in Lonesome Road where the Courier mentions that Navarro is gone - I having played it without FALS complete know that he mentions it as though it were still operational.
3. Tell me if the Courier mentions Navarro is gone.
Can be done on people's first playthough.