The case they're arguing, quite literally, is analogous to this:
I sell hammers.
You can only use nails I sell with my hammers, despite the fact that someone else sells identical nails for less money.
I'm a bit sick of bad analogies, but no, that is not the case at all. If you sell a hammer and used it on any kind of nail possible, that is fine.
Joe's Hammer&Nails sells a 10inch hammer along with super-duper nails that go with it, for sure the best fit possible for the easiest hammering action you'll ever see.
You see a business opportunity cause everyone loves the 10inch hammer, but hates the nails. You make cheaper nails than Joe does, so you decide to incorporate and but thousands of Joe's Hammers&Nails, then re-package the hammer with your nails, and call it kntgsp's Nails&Hammers.
You are now causing monetary damages to Joe based on his own property. You are liable, and thus, Joe can sue.
If you are a consumer, and buy Joe's Hammer&Nails, and use your own Nails, you have caused no damage to anyone, and thus Joe cannot sue you.