THVD1420: Failsafe function with AC termination

Hello,

I want to confrim if THVD1420's internal failsafe still work with AC termination.
THVD1420's failsafe function is just having negative Vth.
When the bus is open with AC terimnation, I think both A/B inputs are just floating and the internal failsafe doesn't work. Is this understanding correct?

Regards,
Oba