Jon tries to have a discussion with Dany about it (and by it, just as a reminder, we’re talking about the carpet bombing of a million innocent lives):
When reason clearly doesn’t work, because wtf is this answer, Jon turns to pleading. He begs for her to show mercy, not only to Tyrion, but everyone else who has opposed her (meaning Sansa):
He’s in tears, begging her while also siding with her. This is 100% Sansa begging Joffrey to forgive her father, saying he didn’t know what he was saying, that he must have been lied to.
What is her response?
“As long as I am your king, treason will never go unpunished.”
Still, I suppose Jon could have asked her opinion on the matter. Oh wait, he does that, too.
No, Jon. They don’t get to choose. But you do.
He had a choice. He made it. He saved his family and probably millions of other people.