Settings:
System Settings > System > Tags
Tagging enabled - Yes
Tag mode - Closed System
Can use a tag as content prefix - Admins only can set prefixes
Member Groups > Manage Member Groups
Disable Tagging Ability - Yes
Disable Prefix Ability - Yes
Members > Manage Members > Viewing Member [USER]
Disable Tagging Ability - Yes
Disable Prefix Ability - Yes
Create a new blog entry with the [USER] and you will be able to see and select the tags from the list.
The tags selected will not be saved and edit view of the entry will not show the field Tags as desired.