I took the question asked by the OP as a request to copy an old thread in order to add new comments in a new thread. To my mind, that is plagiarism. If you want to reopen an old topic, then you should link to the dormant thread, and add comments to justify an updated discussion.
Well yeah, but I think he's asking if it's ok to keep the exact format and update it himself by creating the exact same thread. If he wants to run that sort of thread I think he should just create his own thread and format it in his own way with original work. This would avoid plagiarism.
Hence, as long as he has granted your permission to continue the thread, you can. But then, copying the idea of that thread is somehow plagiarism and stealing of one's intellectual property. Better to search or find new ideas of threads while waiting. And if ever you really want to push urself posting the same thread idea, make sure to paraphrase and properly cite your source. But then again, better not to do it without any further permission with the original content creator. Because, who the hell wants to have his idea being used and stolen wihtout any consent right?
Merely copying the 'idea' of the thread wouldn't really be plagiarism. Plenty of users create these sorts of list/overview threads for all sorts of things, but basically quoting the entire thread and keeping it updated would be a different story. He should obviously get permission from the original thread creator, but that's going to be difficult if the person is awol.
