I *think* there may be a hidden timer, as well. Once they have been wounded/imprisoned, there is a certain time you have to wait before you can arrest them again. Also, they may not still be fully recovered, even though they are "OK".
I have been waiting for him, just in case he really was wounded and there was a hidden timer. But it doesn't seem that way as, since he is a diplomat too, appears to have been slowing down the TO. I still have no option to pick him up, although I should since there is a TO going. Is this intended behavior?