First, Lenovo doesn't receive any money when you buy a used laptop. Second, using a ten year old laptop sends a much stronger message than buying a new, slightly alternative laptop. Third, security is like history - if you want to get it right, you have to wait for rigors of time to reveal the truth. We think that Purism is at least as secure as Libreboot, but we know a lot more about ten year old hardware than something fresh off the fab in China.