They need to show who is deleting them, like many have asked. It's all very well saying demote everyone, but why should we have to. It's not fair on the innocent. Also by doing that is limits the people who can delete tasks, so if you have a co op where there's a minimum point requirement for tasks, you need the leader to be on all the time then. It's no use having only one person being able to delete if they are in a different time zone to other players.
So one person messing up the reserved task, getting everyone demoted and unable to delete low point tasks ruins it for everyone.
If someone is removing reserved tasks, then outright lying when asked, they deserve to be removed from a co op, so we should be able to see who deletes them. Many have asked for this, only the one's deleting them would have reason to oppose.