The problem it's we can have a working configuration but mysqld refuse to start and it's should not because Galera is off.
oct. 09 14:15:02 hb03-mariatac01-new mysqld: 2017-10-09 14:15:02 139748708274752 [ERROR] WSREP: Only binlog_format = 'ROW' is currently supported. Configured value: 'MIXED'. Please adjust your configuratio
with WSREP_ON = off
I am agree if WSREP_ON = ON but with OFF it's should not bklock the start of MySQL server.