If Taylor hasn't certified the Kytch product to safely integrate with the Taylor product, it seems reasonable for Taylor to say it could cause problems. If they said it will cause problems, that seems a bit different.
While it's in the shop, it falls off the lift: $10,000 damage. Now your formerly "broken" car is even more broken? Is the situation still the same?
Defamatory? I don't think so, but I guess the courts will decide.