It can "only mean" that? No way, José. I'm absolutely positive, no doubts whatsoever, totally sure that it means that they can't but by saying that they can't

It can "only mean" that? No way, José. I'm absolutely positive, no doubts whatsoever, totally sure that it means that they can't but by saying that they can't they're trying to get you to think that they can and want their opponents to use something else. My reasoning is iron-clad.