Greg,
At first I thought that you should bond to that lug, but the more I think about it and ask others, the more I guess that it does not have to be bonded to anything. I guess you could use that lug and bond to a fence if you were close enough to the fence.
Normally the contractor wouldn't have a problem coming back to throw a bond wire to the deck box. In this case the contractor is an hour away from the job. As long as the job is safe and meets code and manufactures instructions, then I would be OK with it.
