I'm not sure I understand this:
The default avatars will be from now your staff images. I recommend you to use pictures. They will work the same way like normal avatars,
with the exception that they will be viewed only by your staff. The rest of members will be able to upload their own custom avatars, as usual.
I would like for journalists to use avatars but not to the exclusion of the rest of the members.
Can't I have both?