Dotcom was at worst a white collar criminal. He wasn't a drug trafficker or anything of that nature. There was no reason to expect violent resistance to an arrest. Two or three uniformed officers would have been enough to make him go quietly.

I don't think they did it due to risk of violence, but because he'd hit a dead man's switch and destroy evidence if they didn't shock-and-awe him in the arrest.

A dead man's switch requires inaction, not action. The whole point is that if you don't do something, the action occurs.

I dont know, seems kind of silly. Surely people implementing a dead mans switch would do something along the lines of "if i dont ssh into this box every 12 hours" or something.

Destroying evidence is a crime, so they can always just arrest people who do that for that.

Just to play devil’s advocate:

How is this different from a corporate email retention policy that auto-deletes emails older than 6 months?

I mean, sure, you can be required to override the policy under certain circumstances (e.g. when notified of an upcoming lawsuit), but what if the only person capable of doing that is being held under arrest? (Or just cannot be contacted)

My intuition is that, in the United States, it would be a 5th amendment violation to require an arrestee proactively disclose the existence of such a kill switch.

Calculated risk. Sometimes destroying the evidence is less of a crime than being caught with it.

Civilised society might prefer no weapons?

I personally would prefer not raiding a home with weapons.

I’d prefer the Donald Trump treatment for people who don’t have a history of killing people.