Without knowing the specifics of this thread, I'll make the following observations...
I have a philosophy that I NEVER second guess my tech's decisions that are made onsite without me.
They know that they can call me for any questions regardless of how irrelevant they think it might be and I'll never belittle them for asking. They also need to know I trust them and their judgement and ability to know when to call and when not to.
On the odd ocassion that a client lays an allegation against them, I always thank them for bringing it to my attention and assure them I'll look into it, speak with the tech(s) and if necessary, get back to them.
If you mouth of against your own guys in front of a client, what does that do for your image? When you place a tech in a vehicle to service your clients without you, you're implying to a client that you have faith in your tech by just sending them there, belittle them in front of the client and you've undone that and potentially lost their respect for your tech, you and your company!!
John