Why is there no CONFIG_HOST_1 / STRAP_1 on my Sterling-LWB5+ solder down module?

There is only two pins required to choose between the available interface options of USB, SDIO 1.8V and SDIO 3.3V.

Pins accessable are CONFIG_HOST_2 (STRAP_2) and CONFIG_HOST_0 (STRAP_0).

CONFIG_HOST_1 (STRAP_1) is not accessable. It is tied to GND inside of the module.