The issue is that you already have a remote syslog loghost set and it is not in a configure-esxi supported format. Today, the script allows for <IP>, <Hostname>, <FQDN>, or <PROTOCOL>://<IP|Hostname|FQDN>:<PORT>. The issue is the loghost you have set is in the format <PROTOCOL://<IP|Hostname|FQDN> in short, it is missing the :<PORT>. The vSphere documentation does not make it clear that <PROTOCOL://<IP|Hostname|FQDN> is allowed and the configure-esxi script --help states the supported formats. If you try:
configure-esxi -u vimanager -s vmvchomapp03.domain.com.au -t udp://10.80.9.116
you will see that configure-esxi will not allow it. The problem you are experiencing is that configure-esxi needs to validate the existing loghosts on the ESXi server, but the error message does not tell you what loghost is in the wrong format. I will dig into this a bit more and get this addressed in the configure-esxi script. In the meantime, you will need to change your existing loghosts in the format <PROTOCOL>://<IP|Hostname|FQDN> to one of the supported formats for configure-esxi to work.