oracle lock system account

SQL> show user
USER is "SYS"
SQL> alter user sys account lock;

User altered.

SQL> select account_status from dba_users where username = 'SYS';

ACCOUNT_STATUS
--------------------------------
LOCKED

SQL> conn / as sysdba
Connected.
SQL> show user
USER is "SYS"

SQL> connect sys@ORCL as sysdba
Enter password:
Connected.

SQL> show user
USER is "SYS"
SQL> select account_status from dba_users where username = 'SYS';

ACCOUNT_STATUS
--------------------------------
LOCKED