By default Nexus 3 sets the java.io.tmpdir to a location other than /tmp, but Install4J still attempts to write a file to /tmp and the startup fails if the nexus user cannot write to /tmp, either due to permissions or if a file of the same name it is trying to write, already exists - for example one left over from an unclean shutdown.
A workaround is documented here: https://help.sonatype.com/repomanager3/installation/run-as-a-service#RunasaService-PIDFile
Perhaps this should be added to the default configuration?
To test, set permissions on tmp to only allow the root user to write to it. Attempt to start nexus 3 not as root user. Startup should silently fail.