With low rates of MRSA in the state where the trial was...

With low rates of MRSA in the state where the trial was conducted, the participant numbers were most likely too low to confirm efficacy against MRSA. Note, effectiveness against MRSA was a secondary endpoint. I.e. the study design was not geared to measure this as the primary outcome. However, as you say, previous explant study confirmed effectiveness against MRSA and confirmed that antibiotic resistance doesn't occur in cannabinoids.

The current study was a success because it achieved its primary endpoints: safety, tolerability and effectiveness against Staph aureus. Note announcement 11/11/20 states "Plans are underway to begin clinical development in the US under an IND following the successful completion of the current Phase 2a BTX 1801 clinical study." The study was successfully completed.

The announcement also noted that BTX has Qualified Infectious Disease Product (QIDP) designation and, "The FDA encouraged Botanix to request a Fast Track designation for BTX 1801 following submission of an IND application for BTX 1801."