Turn on car with seats removed?

Greetings! I am new to this forum and have been referencing many threads here for the past few weeks. I personally do not own a Forester but I will be helping a friend install a completely new sound system in his 2015 Forester with the 6 speaker system. I have found many helpful threads regarding stereo install and some steps for seat removal.

What I'm wondering about is, is it OK to turn the car on with the seats removed from the car?

I have done many stereo installs before but never one where I had to remove a seat with an airbag. My main concern is that having the airbag sensor disconnected could somehow make the remaining airbags deploy if the car is turned on. With the seat in the car I don't expect there will be room to set gain/crossover levels on the external amp we'll be putting in and will need to turn the car on to make those adjustments. It may seem like a silly question, but this isn't my car and I want to take every precaution not to screw something up.

Thanks in advance!