I'm of the opinion that possibly an attempt could've been made to hack that account without success before they approached you. Maybe changing or fortifying your password won't be out of order now.

Even if the account is banned, it's inconsequential to the user as it's a newbie account. It's as worthless as a toilet paper. However, the said "buyer" account is only a newbie account by rank, not by registration anyway. It registered in this forum in 2019. So, it's not really newbie in the true sense of it.

There's a reason mods don't like bothering themselves with newbie accounts. They don't worth much to inflict heartache or regret of action on the user. Once nuked, the user just move on and creates another one(s). Trust me, that's surely an alt account. The user dare not use their original account to do that because they know the repercussions of their action.