It's an interesting circumstance: in the sentencing phase of a triple-homicide trial in Texas, the jury initially votes 10-2 in favor of execution. The foreman stands up and reads Romans 13:1-6 aloud. Several hours of deliberation followed, and the jury eventually reached unanimity in sentencing Jimmie Urbano Lucero to death.
It doesn't seem too surprising that the Supreme Court would decline to consider this case. I don't know anything about what kinds of jury behavior qualify as "misconduct" of the sort that renders a trial or sentence unfair. But I imagine that the Bible has surely been invoked (if not read aloud, or if not explicitly cited) by countless jurors trying to persuade their peers over the years. When you put twelve regular folks in a room and ask them to make a decision, they're going to use the tools at their disposal to do their duty. Let's just add that to the longer list of reasons why the death penalty has no place in our society.
So I don't doubt the legality of what this jury foreman did. Nor do I doubt the sinfulness of it. It's a real shame, and it is perfectly legal.