I’m pasting in a relevant paragraph from the article linked to by the person you are interacting with:

Offit offers a balanced judgement on both the Cutter incident and on the Salk and Sabin vaccines. Reviewing failures in the manufacturing and inspection processes, he exonerates Salk from blame and concludes that `the federal government, through its vaccine regulatory agency... was in the best position to avoid the Cutter tragedy'. Three larger companies produced safe polio vaccines according to Salk's protocol for inactivating the virus with formaldehyde. The lack of experience and expertise at Cutter Laboratories, undetected by the inspectors, caused the disaster.

Just for those who might be following along. Your reading of the article linked to lines up with my reading of it.