Currently it is possible to set up permissions so users can "Edit Watchers".
We would like to allow people to ADD watchers, but only allow leaders of projects to remove watchers.
(Of course you should be able to remove yourself from the watch-list of a bug also).
Typically, somebody who is assigned a bug needs input from other people.
The easiest way would be to add these people to the watcher list, and get their input.
When they have given the input, they can take themselves off the watchers again.