Come on, he's a police officer who is claiming he fired because he felt his life and safety were in jeopardy. I don't know of too many cases where an officer failed to walk after claiming that.
I’m not a lawyer, haven’t played one on TV nor stayed at a Holiday in, but I’ve always thought that if you ask for a non-jury trial, you are counting on the judge knowing/following the law, and not ruling with his emotions ie. your defense depends on technical info that a jury might not follow. (Of course I don’t know about this particular judge). If the judge’s family are all L.E. you might be right. But I find it worrisome that for at least the last week or 10 days, there have been people publicly stating that they will tear St Louis apart if the officer walks. Ministers had a meeting with the judge where they said violence was likely if he acquits. At least a jury would likely be sequestered in a case like this.
I have not followed the case and the officer may be as guilty as hell. There is a claim that his (the officer’s) DNA was on the gun but the defendant’s wasn’t, but I don’t know how DNA ends up on a firearm.