Sbus out (from Serial) sends sevo out with Safety Switch off (blinking)

Hello,
I use Pixhawk mini with limited ports. I need SBUS output. To save 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 (the same behavior like SB out on another Pixhawks)