Indeed, not only is this pretty sketchy but the more concerning aspect of it is: why would this guy as the receiver even be trustful of whomever is “selling” him these addresses?  It’s not as if anyone who once held the private key to these addresses couldn’t just retain the information and then set up some kind of an address/mempool monitoring bot that kept an eye on the address’ activities and either front-ran/cancel/reverse the transaction(s) automatically, and drain whatever funds are in there.

Personally, if I had to hazard a guess as to why OP is wanting to purchase such things, it’s due to airdrops. Not for trying to receive any unclaimed airdrops tied to that address (as others have pointed out, that ship has sailed for most of them as the claim period has lapsed) but more likely as an attempt to give himself more “credibility” for the sybil accounts/multiple addresses he’s got going trying to farm some current or forthcoming/expected airdrop(s). I’m assuming he thinks that having the historical activity will help to counter any potential cases of being flagged as a suspicious address or sybil account; on that front, OP may not be that far off the mark.