It can't be made as a command line option without introducing explicit code for splash screens, as the current one is a no-code built in utility of the WPF Framework. Introducing new code can then introduce other bugs. So it would be best to find the root cause of your problem instead of having to introduce these workarounds for a problem that exists for only one user out of thousands.
Hmm, that doesn't quite make sense, because one of your devs had no trouble making a package with no splash screen for me to test. Or is the splash screen a build-time option/setting?