In the last month I've investigated some accounts under the premise of them being bought and/or hacked accounts, and realized that most of the accounts follow some pattern. Most of them had been inactive for some time, had a password reset in 2017 and have very little earnt merit (if any).
Yeah, they were likely hacked. Wasn't there a big bitcointalk hack that year? But either way, we're almost 3 years into the merit system and I don't think there would be much advantage overall if Theymos stripped any of those accounts of merits--plus it would probably lead to an outcry of members suddenly noticing that their airdropped merits are gone. I doubt Theymos wants to deal with a situation like that.
Any damage that could have been done with airdropped merits to suspicious accounts has likely already been done by now.
What if I had an account in 2015 that was very active and made it to the legendary rank... But i lost intrest in bitcoin and stopped visiting bitcointalk in 2016. However, due to the recent bear market i regained intrest in the community, and logged back in today.
Then there's that aspect of the issue. Ultimately there's no way Theymos is going to decide to revoke any airdropped merits selectively, and I don't think he's inclined to revoke them across the board. I hear what you're saying, OP, but this is one of those ideas that's dead on arrival (IMO).