How to Remove Scripts Date Comments from Powershell Generate Database Script?
From the SMO documentation for ScriptingOptions:

IncludeHeaders Gets or sets a Boolean property value that specifies whether the generated script is prefixed with a header that contains information which includes the date and time of generation.

So you should be able change this line of your PowerShell script:

$CreationScriptOptions.IncludeHeaders = $true; # of course


to

$CreationScriptOptions.IncludeHeaders = $false; # of course not