Let us say it is being considered!
We need to implement two more features with the option to do this.
1) the delete-trigger type should remove 'orphaned' rows in the ODBC-source
2) the update-trigger type should query MySQL and the fetch the values to update with.
Agree it would be nice! And I think it could be done with most ODBC-drivers. Not the ODBC-text-driver and I believe dBase and similar 'early' ODBC implementations would have problems too.