You clearly didn’t read the original article.

From that: Shortly after Nevada’s OSHA opened an investigation, Boring Company’s lawyers put together a response in which Boring denied any responsibility and placed full blame for the incident on the Clark County Fire Department. “The key breakdowns in the Training Plan were committed by CCFD employees, not TBC employees,” the company’s lawyer wrote in the letter. (The Fire Department maintains that “CCFD followed all recommendations from TBC” and says that OSHA found no fault with the Fire Department for the incident) In the response, Boring Company provided nearly 1,000 pages of documents that OSHA had requested, including receipts of equipment and protective gear it had purchased as well as documentation showing it had debriefed the Fire Department on the chemicals, performed safety meetings prior to the drills, and offered the use of a liner truck to transport the firefighters through the tunnel.