Varian didn't stop Thoren.
He genuinely didn't care about killing the so-called Lion prince. Or the succession problems of Thoren. These were all distant pasts for him.
As he experienced repeatedly, History had its own momentum. No one, not the Lion prince of today or a Dragon prince of tomorrow could stop the arrival of God Emperor.
But if he pushed Thoren to not kill, the framework of 'benevolence' would fall apart.
The God Emperor who could ally with him against Architect should be the one willing to use force for good reasons—reasons beyond personal benefits.
'I will help you to the best of my ability.' Varian aided instead of obstructing.
Thoren joined hands with a few others in a secret realm during a prince competition and made a move on the Lion prince.
It was confirmed then that the Lion prince was indeed maintaining a facade. He was neither kind nor gentle.
The God Emperor was vindicated.
