Even if it is just a franchise this is outstanding visibility for bitcoin. I'm sure lots of people who visit Burger King have never heard much about bitcoin and so to see it being accepted in a mainstream outlet is a good thing!
Eh, maybe to an outsider. In reality, though, people should understand how businesses work. I can pay a small sum of money to get a franchisee license for McDonald's. I can then tell people I accept BTC. That doesn't magically make McDonald's accept BTC -- it just means I do.
In the case of this, Burger King doesn't care if the owner accepts BTC, Zimbabwe dollars, or rocks -- they only care that they are paid in fiat, in the proper amount, every month. They don't care where it comes from or how he got it.
It is very nice. You can make Bitcoin more popular and that is very good. I hope that more people will use it.
After they saw that you can pay with Bitcoin in the Burger King. Maybe Mc Donalds or something will do it also.