If we're going by the WN then the plot point actually has been foreshadowed in earlier chapter,
This manga already departed far from the WN, though, so who knows.
Justus don't have the authority to just pardon a traitor. He's a researcher, not any high-ranking nobleman. He does however have the authority to use a criminal as a test subject, and even then, he needed to call in a few favors.
He's doing what he can do to stop Harold's execution within his...
I don't know, that's how Mangadex made it when I clicked reply, I didn't recheck it.
That might be true in the real story, but that's not true in his narration. I was talking about the narration, since you were saying that even in his narration, he admitted to forcing Harold. He didn't force...