Wow, sucks to hear, but glad everyone is ok.
Can you elaborate on "the brakes went out"? If there was an issue there, whether design or maintenance, it is a service to all of us to share why they failed, since whatever it was applies to us too.
As far as airbag deployment, if you came out without a scratch, then the airbags did their job either way. You don't want them going off if they don't absolutely have to. Hitting the bags is like getting punched in the face. It is common to have your entire face bruised and burned by airbags (especially airbags from the late 90's, when they weren't as highly evolved as they are today).
That's not to say that they were working perfectly, the sensor could have been faulty, but since you didn't get hurt, that was the best outcome. The brush guard may affect the deployment, but the sensor for actuating deployment is an acceleration gauge, so the way the brush guard would affect it is to absorb some energy before the bumper is hit, which reduces the acceleration on the sensor, and on you too. That doesn't mean the brush guard is safer, but in some cases, it may absorb some extra energy.