[rainmaking]

> the author's argument seems flawed

Author here.

> So the government might as well be the arbiter of all transactions

Take a narrow view of what it means to be arbiter of all transactions. You can't freeze or modify balances, and you certainly can't intervene and pretend you didn't. You can merely decree, power of your authority, that transaction A arrived at your server before transaction B did, and you can certify that transaction A complies with the software protocol accepted by law, and you can reject transaction C because it doesn't. That's your mandate, that's it. Everyone can look at the public log and make a fuss if you didn't follow the law to the letter.

In practice, how is this different than relying on mining to avoid double spends?

Sure, in this scenario, government is capable of chosing a more invasive policy, or becoming corrupt, but choses not to. But government could just as well ban electricity use for mining, or accept bribes to permit use of specialized mining equipment, but choses not to. Bitcoin is already completely dependant on arbitrary political decisions- negligably less so than taking the job of implementing narrow arbitration.