2013 Ford Fusion "Pass Airbag" indicator illumination behavior

[Chaotix]

The "Pass Airbag" indicator on the top of my dashboard only illuminates "off" when the seatbelt is connected to the front passenger side and no one is sitting in the front passenger seat. I'm wondering if this is normal behavior for this indicator?

I did some testing:

front passenger seat belt connected with no one sitting in the front passenger seat - indicator illuminates "off" passenger airbag off?
front passenger seat belt connected with someone sitting in the front passenger seat - indicator does not illuminate "off" passenger airbag on?
front passenger seat belt disconnected with no one sitting in the front passenger seat - indicator does not illuminate "off" passenger airbag on?
front passenger seat belt disconnected with someone sitting in the front passenger seat - indicator does not illuminate "off" passenger airbag on?

Also did a test where I disconnected the plug to the seat belt buckle and the indicator did illuminate "off" until someone sat in the passenger seat then it did not illuminate "off"

Could there be a bad module somewhere or is this normal? I would think the passenger airbag indicator would be illuminated "off" if no one is sitting in the front passenger seat or the sensor doesn't sense enough weight on the seat regardless of whether the seatbelt is connected or not. As of now I feel the passenger airbag is "on" even when there is no one in the front passenger seat.

I tried changing out the entire seat with another one with the same results as well as changing the actual front passenger seat belt buckle with a used one - same results.