Right. It's also not the case that "51% of miners must confirm the transaction". Only one miner has to include your transaction in a block and "solve" that block (ie find a nonce such that the hash of the block header (which includes the nonce and a fingerprint of the transactions in the block) is less than some number), to have it officially added to the blockchain. Of course, most people wait for a few blocks before accepting the transaction as truly confirmed to protect against the possibility of some other blocks being released that replace the one with your transaction. It takes 51% to be able to guarantee control of what new blocks are added to the blockchain.