A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
it does not lock Text Edit as standard.
When you set the built in Locked flag the XML looks like this
To lock textEdit you would have to manually edit it
Obviously there is a learning curve to do the edit but you sound pretty knowledgeable.
Sadly there are still ways to edit the text even with the lock set but it is at least more di9fficult