It strikes me that a better solution is to fix whatever tools we're
using to determine what still needs to be reviewed. If someone is
checking all revisions marked as "new" and needs to mark things they
won't review as "deferred" to get them off the list, maybe they should
instead be checking all revisions marked as "new" from particular
paths. Then explicit deferral will not be necessary, and projects
like SMW can go ahead and use Code Review at their own pace without
annoying anyone else.