The packages do not know the difference between a server and a workstation. This is why there is no warning about what you are installing to.
From what you've stated it sounds like you either have exported installation packages from the SEPM server, or you are running the installation that is included in the downloaded media. If you ran the install from the downloaded media this would be an interactive install and would walk you through the installation process. An exported package could be set for interactive,
If you are running an install exported from the SEPM it may include custom feature sets, such as not including NTP or PTP in the install. Simply because this package may be named ServerSetup.exe does not mean that it can only be installed to a server. It simply means that the package was named such to associate it with what features you want installed to servers.
Since our product supports both Workstation and Server oprating systems it is not going to, by default, throw any errors. You could possibly modify the MSI with ORCA to create an OS specific requirement however this would be unsupported by Symantec and a do at your own risk scenario.