The relationship between a franchiser and franchisee is more like vendor and customer.
The franchisee pays a fee to the franchiser, based on gross sales. In return, the franchisee gets marketing, brand recognition, etc. McDonald's also provides supplies, but the franchisee pays them for it.
This is nothing but grasping at straws. The NRLB knows they have no precedent, but are hoping to find a friendly judge that is willing to twist the law to suit them.
Or, they are hoping that McDonalds will settle -- thus providing the precedent they need.
They'd have to be nuts to settle - this threatens the lifeblood of the company. MCD is extremely franchise-heavy, and light on corporate-owned stores, which is why they're so profitable relative to their competitors. A settlement would open the door for more such encroachments. They need to put the NLRB in its place.