QA-2M-2: A disc supported by the target is not subject to the two-meter rule. What about a disc supported by other course equipment such as a tee or course sign?

That is still subject to the two-meter rule, as it is not a target. The only exception is the target for the hole being played, so if you somehow manage to get your disc stuck above two meters on a target for another hole, it is subject to the two-meter rule.