Intamin doesn’t make cable, it buys it, so there claim is irrelevant. Intamin’s design failed to provide guarding to prevent loose and broken cables from moving into areas where uneducated folks are expected to be present.
However, do you think whether Intamin makes or buys the cables is relevant to the question of Six Flag's proper replacement of the cables? All that I'm suggesting is that one would assume that cables purchased from Intamin would meet their design specs, whether manufactured by Intamin or not.
If Six Flags replaced the cables with ones that failed to meet or exceed Intamin's specs, then don't you think Six Flags could be held liable for negligence in its cable-replacement choice? That question is independent from Intamin's liability for negligent design.
I was attempting to say that Six Flags better hope it was quite careful in replacing cables with ones that met or exceeded the specs of the ones it would have purchased from Intamin. Even if it maintained the cables religiously, if it used an eight-strand cable instead of a ten-strand, or a cable that was 1/32" smaller in diameter . . . you have a happy plaintiff's lawyer.
None of which minimizes your correct observations about absence of a guard
Sometimes I'm as incoherent when I write as I am when I talk. The only different is that my fingers don't drool on the keyboard.