Praising someone for their commitment to their principles, regardless of what those principles actually are, invites a kind of twin sickness.
First, it obfuscates the necessity of *good* principles. If simply having some standards that one commits to (whatever they may be) is praiseworthy, then we undercut our ability to encourage people for having good principles, or discourage those who have bad ones.
This leads to a compensatory measure: by denying that people with 'bad' principles are really principled at all. Hitler did not sincerely believe he was doing the right thing - if he did, then he was principled, and we can't have -that-. Instead, he had to never really believe what he was saying, and the whole thing was just a bid for power and glory, or maybe just madness.
Play that game and you can at least describe a world where only people beholden to 'good' principles really exist after all. Convenient!
But if it's not true - and if it's easy to realize that it's not true - then you're setting the groundwork for a horrible and confusing culture of misdirection and mistrust.
Which, to a degree, seems to be exactly where we are right now.