That wasn't what I was saying at all - every profession has its fools and scoundrels, however most are good and honorable professionals. What I was saying is that Chase's moving to a judgeship where his ruling might have to run counter to previously held position is not at all unusual and does not create bias per se as you assert.
"Ex Parte Milligan has nothing to do with what we are talking about."
You've alleged that the opinion was biased simply because Chase had been in the Lincoln administration as though that fact alone made it so. The logical implication of that assertion is that he was just rubber stamping Lincoln policies and furthermore that he was some sort of puppet-master controlling all the other justices since they were mostly Lincoln appointees as well. My comparison with Ex Parte Milligan demonstrates that, contrary to your assertion, Chase was independent and would rule against Lincoln administration policies if it were appropriate based on the law. As for Texas v. White, two of the five in the majority were not Lincoln appointees so you can't allege bias based on that and two of the three dissents were Lincoln appointees which further undermines your allegation. Without Chase, if either Nelson or Clifford had switched their vote, the ruling would have been different, but they didn't and there is no "bias" that you can blame on their part. There is a reason that Supreme Court justices are appointed for life - so that they can rule independently and without being beholden to anyone and without fear of reprisal. As for Chase being able to control his fellow justices, I'm guessing you haven't met many judges - they tend to be fiercely independent and become moreso the higher they go, frequently disappointing those who appointed them. For contemporary examples, John Paul Stevens, Sandra Day O'Connor, Anthony Kennedy and David Souter all come to mind.
"Were Davis and Stephens citizens yet?"
Doesn't matter whether they were or not. They had opinions and freely gave voice to them. The Wikipedia reference that you linked to stated "Based on his previous position, many southerners questioned Chase's impartiality and believed he should have recused himself from the decision. While legally binding, the court's decision was extremely controversial and remains so to this day. Many former Confederate officials such as Jefferson Davis and Alexander Stephens as well as legal theorists such as Lysander Spooner rejected the court's reasoning and defended the right of states to secede." Again, I don't hear Davis and Stephens and "many southerners" rejecting Chase's reasoning or accusing him of bias based on his ruling AGAINST the Lincoln administration.