This whole thing reminds me of the film, "Falling Down".
I think the old dude had just had enough, and his patience for all the little B.S. in life finally ran out that day. The guy snapped. Mr. Texter just happened to be the one to pull the ripcord. Looking back at my life, I have FAR less patience for rudeness and bad behavior then I did in my 20's and 30's. The "Me" attitude that seems to pervade society today drives me nuts. If I hit 80, I fully expect to be sick of the whole thing and deep into "codger mode".
I guess the lesson to be learned here is: Watch out! Act like an ass all you want, but you never know when you'll be the last ass in a long line of asses and get your ass handed to you.