Tuan,
Using the option the way you've shown, only the AP that has lost its link status will shutdown the WLAN.
If there are other APs beaconing the same SSID, those APs will continue to run the WLAN.
Also, when you say that you've disconnected the LAN, what exactly did you disconnect?
This option is useful in situations where an AP is still receiving power, but the Ethernet link has been broken between the AP and the switch.