SBUS out active when safety switch is "OFF" - blinking

Hello,
I use Pixhawk mini with limited ports. I need SBUS output. To safe serial ports I change RCIN (Serial Port 4 - UART 6) to SBUS out, with inverted TX. It works, but what suprises me, that servos connected via this SBUS out are moving regardless to safety switch (of course BRD_saftey_mask is set to 0)
Any thoutghts? or normal behavior?
The best should be probably no sbus output when safety switch is blinking.