I don't know if he noticed the date of the original thread or he just filling up his weekly quota for the Signature campaign.
Except the thread is a stickie, the poster would have gotten the warning, that the thread they are about to reply to has not been posted on for over 120 days, and they should reconsider if the want to reply or start a new thread on the topic.
Although the reply was constructive, but who knows if the OP still alive?
Is there a possibility that the reply would still be relevant today and helpful to other members who may have a similar inquiry?
Waking dead threads may be unethical in some situations, but a user could have a valid reason for choosing to do that, I think there are much easier ways to spam than digging up 8 year old threads.
*Edit: Issue solved. I'll also vote for that thread to be locked to prevent future bumps.