He says there is good reason to believe that he shouldn't be the owner of the account anymore. Although yes, he does say that he doesn't know with certainty either way, the preponderance of the evidence does support it not being hacked.
Nope. All that confirms is that he was able to produce a signed message from an address previously associated with his account. Additionally, Light mentions that the signed message is from a cashed version of a thread, which implies that the post that included the address was deleted. I was in communication with him for over 3 days before the account was actually purchased, the bayuo account was created very shortly after the account was sold, so if the account was in fact hacked then the hacker would have needed to gain access to the actual password of the account, not change the password, both send and receive PM's to me without the "real" owner of the account noticing, and then bayuo would just so happen to know which thread an address was posted on despite not being able to search for such address because the post was deleted. Also the "real" owner of the account would have had to not noticed PM notification emails received any time I had sent the account a PM.

Can I ask if you seriously think all this would be plausible? It should also be noted that bayuo claims to employ extensive security measures and claims to have used a very long/complex password. It should also be noted that there was no corresponding report of theft of bitcoin from bayuo and he never reported that he found any malware.