Most times, those accounts are not used by the original owners of the accounts. They are either bought or hacked, so it will be difficult to completely stop this form of illicit activity entirely. However, I believe the secret question should be asked when old accounts that haven't been active for years try to log back in. This doesn't matter if they logged in to the account with the right password. Before they are allowed to post, they should give their answer to the secret question.
But why exactly? What would secret question achieve here? With it both the hacker and the original owner would be locked out of the account. The secret question is a kind of failsafe intentionally placed. Did you mean the secret question would be forced on the inactive user? And after getting self banned through the secret question (nobody remembers the answers IMO), they would need to appeal and sign a message to prove ownership and regain access to the account? Something like that?