I had hoped that using those URLs we would find copies of the pages from January on Wayback Machine, but not there.
I agree with the suggestion to file a complaint through the CFPB. The CFPB does not assess the merits of these complaints, they forward them to the bank which must respond. The value is that the issue will be seen by a different set of people at Chase. Make the claim dead simple and short: "I was promised 38,595 bonus Ultimate Rewards points if I purchased a Pelotron Tread and paid with my Chase Sapphire card. I did this but was denied the bonus by Chase's marketing department because (they say) Peleton published the offer prematurely. Peleton had the apparent authority to make this offer. Chase has a duty to honor it."
I'd hoped the wayback machine would help too and tried multiple times to track down any of the earlier versions of the webpage.
Great suggestion with the CFPB. I'm going to file a complaint today and hopefully new eyes on it will get some traction or more of a response on it than "sorry, tough luck."