Well, there IS one thing you can do. Don't fly on United. I'm in the charter air carrier business now and we would never subject anyone to that kind of wait. Unfortunately it's way too expensive for most. I feel for you - I probably would go for being arrested by TSA before I sat for six hours.
When my mom died recently, I discovered that she had accrued more than 200,000 frequent flier miles. I didn't even attempt to acquire them; I hate United THAT much. The only reason I flew United THIS time was that a friend I was traveling with did the booking. Never again.