Now if you offered a fee to a miner and an exclusive right to mine that transaction rather than broadcasting it to a network, that would be something at least.
That's exactly what I'm proposing. Was I not clear on that..?
You have to change the bitcoin protocol and build your own bitcoin network to do that. Then you have to create demand for your currency by offering value in exchange.
If he was just adding a transaction fee, he wouldn't have to change anything. He would just have to send it just to this one miner, whoever that was, rather than broadcast it to the network. As soon as that miner solved a block with that fee in it, he would claim the fee.
All the same, this wouldn't count as zero-interest. Instead of paying interest to the lender, which makes sense, you'd be paying it to the miner instead for some strange reason, but you'd still be paying it... It seems he doesn't really understand how Bitcoin works.