Currently the check box ‘Protect object from accidental deletion’ is set on the Object tab via ADUC, the value is not visible in AR (MMC or WI).
The same behaviour can be observed for the group’s "Manager can update group membership" check box.
This is by design. Currently AR is unable to read external permissions. An enhancement request (TF00431951) has been created detailing the feature.
Set the check box ‘Protect object from accidental deletion’ via AR MMC console or WI instead of ADUC.
The product team will evaluate the request and this feature may become available on a future release of the product.