well if the status is caused by armor, that means the monster was attacking someone in order to get status'd. Wouldn't the monster remain belonging to that person? I don't see why ownership would suddenly stop just because you status'd the monster.
If I'm wrong, I apologize for the incorrect info, but it doesn't seem to make sense for it to work any other way.
When a monster is status'd, it loses all aggressiveness. If it's a normally passive monster, it'll go back to being passive. If it's normally aggressive, it'll attack whoever it sees first. If it attacks the new guy, then it's the new guy's monster. If the new guy attacks it first, then it's the new guy's monster.
Of course, any decent player should never let that happen. Unless they like... freeze it and sit down for SP or something :/