The point is not that it is being used, the point is that corporations must protect their trademarks or else they may lose the exclusive rights to them. Intel also still uses the “Core” branding on their modern CPU’s so it wouldn’t be a stretch for them to try and continue legally protecting “Core 2 Duo” under the guise of retaining the “Core” part of their trademarks.
The point is not that it is being used, the point is that corporations must protect their trademarks or else they may lose the exclusive rights to them. Intel also still uses the “Core” branding on their modern CPU’s so it wouldn’t be a stretch for them to try and continue legally protecting “Core 2 Duo” under the guise of retaining the “Core” part of their trademarks.