A literal design is not the same as a style. 1000's of people have been biting off chunks of Apple's style for years. Spend a 2 minutes on Dribbble and you'll see that MANY designers have the same style without ripping each other off.

the point was the the specific application of a style to solve a specific problem — that decision — is what is ownable. So to apply that idea to this situation would mean that a company that offers a somewhat similar product to a similar audience uses a similar style. Implicit in the idea of good design is that design decision are specific to the problem they solve. As an isolated set of elements, the UI kit seems fair to me. It's only if it is applied to a competitive product that it would I would call foul. Just my 2 cents.