There is a section dedicated for such offers:
https://bitcointalk.org/index.php?board=93.0Judging by the post in a wrong section you might be new to the forum, so I'll warn you that if someone finds out which accounts were bought you'll receive negative feedback and it will ban you from joining sig campaigns, which I'm guessing is the reason for buying.
Why are you warning him in any way ?
This user will definitely be a toxic addition to the community so we should by no way encourage them or provide them with helpful information.
Just my two cents on it.
That's just like saying all Muslims are terrorists. Just because he wants to buy an account doesn't mean that he is going to be a 'toxic addition' to the community. I have a lot of friends that have bought accounts and are posting well on this forum. It seems like you have a strong prejudice towards people that want to buy accounts. I don't condone buying accounts either, but I don't really have much of an issue with people who want to buy them.