[bumby]

>legal to interfere in the relationship between the franchisee and Taylor?

I think the term is "tortious interference" but it is notoriously very difficult to have upheld in court. You can obviously compete but you can't deliberately undermine a contract with a competitor. IANAL, but from my reading of the article, that would rely on how substantive the safety claims that McD made are in disincentivizing the use of the 3rd party equipment. (not to mention they party wasn't explicitly named in those safety communications)

https://en.wikipedia.org/wiki/Tortious_interference