My guess would be the simplest way to check:
Does user have a currently active subscription?
If yes, they can post
If No, they cannot post
A lifetime subscription should mean a person could disappear for a year (sent on active duty, RL getting majorly in the way) and be able to come back with their characters and everything as they were because its an active subscription. If that is not the case then its not a Lifetime account. Its a "we took a lot of your money but you didn't play in a few months so we deleted your characters, good luck with starting over and all" account. Which it many cases could have the player say forget it and never coming back.
Is there many games out there that offer lifetime subs that will delete your characters if you don't login every so often? I know LOTRO doesn't delete your character (at least they haven't done so yet), I don't know about CO though. I suppose if they do though, it would set a bad precedent for STO also.