Well, if they disable ranked entirely, or disable the item (if it's even the item that is bugged, which I'm not convinced it is), they'd potentially be letting the entire playerbase know about the exploit and possibly other, less obvious exploits that might be out there. Not everyone looks at the server status page or the forums, which are the only two places they've officially acknowledged the issue to my knowledge. Not everyone will encounter a player using the exploit.
If they leave ranked up, people are going to lose games due to the exploit, but the overall exposure to the community could be significantly less. They can continue deleting "redundant" threads about the exploit and basically just keep doing damage control until they figure out how to fix the problem and get something in place. People who have not been directly affected by the exploit will just go about playing like they always do, as if nothing ever happened.
From a PR standpoint, the 2nd option is probably more beneficial to them. Of course, this is just speculation... they may have entirely different reasons or want to put an entirely different spin on it (ie: leaving ranked up to catch more people who would use the exploit, which sounds great to players who want cheaters banned, but sounds pretty dumb from a business standpoint if you're talking about tempting your customers to break your ToS and then banning them).