Honestly, that is enough for me to call it appalling and negligent. I almost caused a bad accident reaching for a cassette one time a million years ago....still feel the fear and anger over what I almost did out of carelessness.
As for his intent, I cannot judge and assume he was careless with weapon and DUI. Any way I look at this he made a very bad decision.
DUI and guns are two things which can cost lives regardless of intent.