Statement: for an attacker to change history, they must solve computational puzzles at a faster rate than the rest of the participants combined
I will answer my own question for anyone that might be wondering the same.

If a majority of CPU power is controlled by honest nodes, the honest chain will grow the fastest and outpace any competing chains. To modify a past block, an attacker would have to redo the proof-of-work of the block and all blocks after it and then catch up with and surpass the work of the honest nodes.