There may be an easier way to get there, but
http://wikitree.sdms.si/default.htm (I always get an error when I click this, but just click ok and it works) Go to Watchlists, click the buttons, then scroll down to the errors that say 803 Almost empty profile.
I think (not sure) this will catch them, unless of course there's a lot of other stuff in the profile.
Welcome to wikitree! At this time I don't believe there are any search parameters that can be set to limit according to specific wording in the Biography. I could be wrong though. However I can think of 2 suggestions. Both are kind of intertwined with each other.
1. You can use the regular [[Category: Needs Biography]] this is found in the Maintenance Categories Than when you bring up that category you can select on the right hand side at top of screen "Limit to watch-list"
2. You can utilize a personal category Personal Categories and set it up specifically for the accounts of which you manage.
Hope this helps