I bought this SUV with the airbag on. I have reason to believe that its wheels were seized and was towed to a garage. Does the procedure to loosen the back wheels have any effect on the back sensors for the airbag?
The simple answer to the question is NO, nothing you do outside the vehicle will cause an airbag fault.
If the question is actually WHY is my airbag light on, then that is most likely not going to be solved here without knowing the error code. Take it to a reputable mechanic or dealer.
HOWEVER, the majority of airbag problems are related to wire connections. The airbags use a low voltage system and consequently the connectors tend to corrode over time. Then at some point the wire or connector is disturbed and the connection is broken. It could be as simple as someone moving a seat back all the way that disturbs a connection that was questionable.
There are few different products you can use to clean up those connections, but personally I use STABILANT 22. It's a contact enhancer and it is amazing. I does not really clean, but it enhances the connection when an electrical current is present but will not create a short. I have used it to fix airbag connections on vehicles that "needed new airbags" as reported by dealer service departments.
Just remember, ALWAYS DISCONNECT THE BATTERY before doing ANYTHING with an airbag system. Having an airbag explode in your face, especially when you are not seated in the driving position can kill you. That's certainly no fun at all.