the fact they won't tell us why is the concern.

"no one uses it and there is a bug" may invite more questions or panic, but "that's all we're going to say" implies that Mythos found something scary, or that the NSA demanded they all get turned off.

AMD is spreading FUD by not answering why it was removed. They could stop this in its tracks if they wanted.

Why call out FUD when you only have more/different uncertainty to offer?