Update two columns of two tables using inner join
You should break your UPDATE statements into two parts

--Update A
    UPDATE A
      SET 
          A.isActive = 0
    FROM OperatorGrouping A
         INNER JOIN OperatorGroupingSteps B ON A.group_id = B.group_id
    WHERE A.group_id = 9;
--Update B
    UPDATE B
      SET 
          B.isActive = 0
    FROM OperatorGroupingSteps B
         INNER JOIN OperatorGrouping AB ON B.group_id = A.group_id
    WHERE A.group_id = 9;