From what I’ve read it’s quite easy to test for the antibiotic resistant pathogens that were involved in the death. It’s part of most FMT screening guidelines, including Openbiome’s — the main US stool bank.

The real problem was lack of oversight, standards, enforcement, by the FDA. So a group of people were doing a clinical trial without the necessary expertise and knowledge. See discussion & links: https://removeddit.com/r/HumanMicrobiome/comments/c1oh0v/fda_suspends_clinical_trials_involving_fecal/