Having removed the worldwind module, the splash screen process now completes but the Snap window never appears, despite the process not exiting.
Looking at the logs, they are full of "no splash screen available" errors. I have attached the log file from an attempt to launch with the --nosplash flag. This was run on a VM running Debian stretch, but a nearly-identical log was produced on a CentOS 7 VM. The only reference I can find to this error message online is a NetBeans bug report that claimed the problem was with Unity-Mir, which can't apply to this situation.
messages.log (72.0 KB)
Oddly, I've got the same installation to run fine when tunneling X11 over an SSH connection to the VM, which leads me to suspect that this is a problem specific to our VNC connection to the VM host, which you're unlikely to be able to diagnose. I know very little about Java GUI frameworks, though, so it's possible there's an easy fix I'm missing here.