Joel Thomas is back as RB coach

Yep. They can block them or choose to let them happen. The Saints allowed Kubiak's offensive staff to take lateral moves.
"Thomas, 50, becomes the third running back coach in three years to leave Daboll’s staff voluntarily after only one season with the organization."

The Giants will be on their 4th RB coach in 4 years. I wonder what's up with that. I do think it's good business to let guys go if they don't want to be there but man that's a lot of turnover.