Anyone can apply for a patent on anything, just as anyone can sue anybody for anything. And of course the cartridge’s name can be protected by copyright. It’s impossible to say if the US (or any other country’s) Patent Office would grant a patent to Schuster based solely upon dimensions of the cartridge. My opinion is that they would not, as there is no “Invention” that I can see. You could theoretically attempt to patent a baseball with a diameter of 1/4" greater than the official diameter, but it would still be a ball, as there is no “invention” incorporating a new design or application of new technology having commercial benefits. However, if this cartridge, or some component of it, possessed some beneficial and novel technology or a new design (neither of which seems to be the case), then it would be patentable.
I can’t understand Schuster’s thought process in basing a patent application solely upon dimensional claims, when such a patent, if granted, could be so easily defeated (assuming any one wished to). Plus what possible commercial benefit to Schuster could be gained? If a patent were granted, no one, except for possibly Schuster himself, would ever bother to manufacture the cartridge if a royalty payment was required. Of course, if successful in his quest for a patent, Schuster could grant limited or broad free use licenses for its manufacture just to appease his vanity. The whole thing is a lame and pointless idea.