I think you'll find he was delisted from the Cows prior to the 2021 season, and played all of that year for Woodville-West Torrens in the SANFL.Only in the year you come out of contract, is my understanding.
Stengle was delisted by Adelaide in early 2021 and listed by Geelong before the draft later that year.
He was signed as a free agent by Geelong prior to the ND after spending the year in the SANFL.