It's not instead, they can file the judgement on the pleadings and if they lose they can file motion to dismiss (most jurisdictions they can combine the two motions, motion for judgment of the pleadings and in the alternative motion to dismiss). It's not much of a legal cost and they stand to gain a lot .
I'm not familiar with medina county, ohio motions practice :)
However, let's assume this will end up in federal court because ebay/et al will remove it there (there is complete diversity, ).
Past that, I won't claim it's not common federal motion practice to combine 12(b)(6) and rule 56 motions, or 12(b)(6) and 12(c) motions.
Yes, a 12(b)(6) and rule 56 motion can be filed at the same time, not one instead of the other.
However, in the 12(b)(6) and 12(c) case, often one is clearly instead of the other, because 12(c) is only used after pleadings are closed, and 12(b)(6) would have to be made before a responsive pleading if one is required (if no responsive pleading is required, yes, you can make it whenever, including at trial)
Just because you can combine them into the same motion out of simplicity doesn't make them not "instead" of each other.