[mrkstu]

Which would make no sense, since it would be a circular argument that would apply to every company with a product to sell.

[fooey]

It's the argument that the car makers lost when it was determined you're not restricted to only their mechanics when it comes time for a warranty claim.

Ford can't restrict you to only Ford parts and Ford service mechanics and Ford Gas and Ford toll roads just because you bought a Ford.

[summerlight]

I agree that it's not very intuitive. That's why there's no single clear definition of "market" in antitrust laws and most of the time it's done by hypothetical monopolist test, which is a highly data-driven process. I have no idea on what will be the final decision since it's not a predictable one for the outsider; I am just giving you one real possibility rather than ruling it out from the beginning.

[anoncake]

How so? Most goods can trivially be substituted for another of the same category. A dishwasher can be substituted for another dishwasher etc.