Get-Command -ListImported is *broken* in PowerShell 5.1
As of PowerShell 5.1.14328.1000, the core Get-Command command is improperly IMPORTING modules when run with -ListImported, so that it ALWAYS finds the command.
For example, the following series of commands will always return the command and the module, when it should return neither:
Get-Command Get-ACL -ListImported
Joel "Jaykul" Bennett commented
Actually, it appears that this is broken since PS4 at least.