Death is a known possible outcome in most SWATers' minds, and they often make jokes to that effect, or jokes about killing people's dogs (and dogs have indeed been killed due to SWATings). They'll often make false claims like "someone is being held at gunpoint, it looks like an automatic weapon". They're knowingly gambling with people's lives when they claim there's an active hostage situation in someone's house. This is not just a prank or hoax.

The SWATer absolutely shares responsibility for their death, even if they don't hold sole responsibility. 20 years seems like an appropriate sentence to me.

As noted in another comment of mine, they didn't blame murder on him, but instead prosecuted more technical, less interpretable crimes.

I agree that murder may be an excessive charge given lack of intent, yet in the United States murder is often broadened to include committing a serious crime (felony) where there is a clear danger of killing someone, and it resulted in death. Then again, I would argue that this goes well beyond just a 'prank call' in that there is intent to specifically victimise someone by deceiving armed agents.

If his idea of a harmless prank involves subjecting someone to that kind of danger then I’m not so sure. Another fun prank: kidnap someone and hang them on a cliff over a lethal fall, with a 80% chance they’ll survive.

Repeatedly threatening someone with death falls under torture.

I rather doubt even 0.1% of swattings result in deaths, how can you compare that to a 80% chance of survival?

Citation needed. Without going any further SWAT--of what I've read, this was back in 2011--shoots all dogs on sight, as soon as it enters the building, as standard operating procedure.

Number doesn’t matter so much, I just personally don’t want to be swatted. It sounds horrible and traumatizing.

You're right, it should have been life in prison.