Do you have actual proof? Have you been targeted at the same time? Have you tried doing at a different time? Do you notice other people doing their convoys and not getting plundered by him? There's always a chance you both happen to be available at the same time for the past year.

You can accept convoy missions up until 2PM/10PM. However, if you accept a mission before that time you can run the mission as the you only have 30 mins to finish the mission. The true end time is at 2:29-2:30/10:29-10:30 but that's for people who manage to accept before the period ended. So let's say I accept a mission at 1:56, I have until 2:26 to finish. Most people would wait in the group before going out.

The "deal with it" is what people have an issue with. My experience is that those that can't deal with it weren't going to last long playing these type of games anyway.