TPS3823A-33: TPS3823A WDI function

Part Number: TPS3823A-33

Dear Sir 

As below Figure1 ,the watch dog function will be asserted after Td

If we use a mosfet to isolate between WDI pin and MCU ,could I extend the Td time ??

If the WDI pin is float ,the watch dog function will be disabled , is it right ??

Thanks