Arthur as grandson of Ambrosius Aurelianus

A number of genealogies indicate Arthur was a grandson of Ambrosius Aurelianus, see Arthur’s descent from Cunedda. There may be an oblique reference to this relationship in DEB 25, following on from the reference to Ambrosius:

“… cuius nunc temporibus nostris suboles magnopere auita bonitate degenerauit …”
“… whose offspring now, in our times, has greatly degenerated from his grandfather’s moral excellence ..”