I don't think Bland and Yikes killing Adam contradicts the message of the series and Bland's character

The series has a message about life being precious and should be protected.
Ok, so from there it seems like there is a contradiction of themes.

But the truth is that no, Adam goes against the idea that life should be protected. He is a terrorist who wants to kill innocent people and enslave humanity.
We could say that in the end he lost everything, but still, he wanted to kill Blake and Yang.

If life is precious and should be protected, why wouldn't Blake and Yang be justified in killing Adam? What they did was protect themselves.
For Blake, Yang's life is worth protecting, and vice versa.

Now, as for Blake's character. She hates the violence of the White Fang.
But think about it, how does the White Fang use violence? They use it to hurt innocent people, they use violence through terrorism.
Blake is against that.
She is not against violence in general.
And really, has it ever been established that Blake is against killing someone? She then feels some remorse over Adam's death, but understands that she did the right thing.
The truth is that it's one thing to kill someone innocent, and another thing to kill a terrorist who is trying to torture and kill you.

Also, I feel that the series leaves a good message in showing that there are people who deserve to die.
Adam is a monster, people like him deserve to die.
Killing Adam sends a message that it's the right thing to do to eliminate scum like him.

My problem, per se, is not with Adam's death, but with the way he dies.
He would have had to have had a confrontation with Weiss, for example.
And Adam's death would have had to have had a bigger impact on Blake, beyond a vague mention of that.