Out of curiosity I googled a bit for spoolsrv.exe and 6160, and seems indeed that it's a tcp port that the spooler service may use, even if I didn't find any more detail. So, probably Nessus has spool service in its database, so it lists this port as belonging to the spooler service. It's interesting nonetheless, as we may have a port conflict with another product...
EMEA Cloud Architect @ Veeam Software
Veeam VMCE #1