Run remote PowerShell Office uninstallation script

KB2956128 is causing headache for users in my network. I do not run WSUS in this environment so I was going to employ PS script to take care of uninstallation. By all means the script below should work

$comp = 'PC03'
$scrblock = 
{
$TitlePattern = 'KB2956128'

$Session = New-Object -ComObject Microsoft.Update.Session

$Collection = New-Object -ComObject Microsoft.Update.UpdateColl
$Installer = $Session.CreateUpdateInstaller()
$Searcher = $Session.CreateUpdateSearcher()

$Searcher.QueryHistory(0, $Searcher.GetTotalHistoryCount()) | 
    Where-Object { $_.Title -match $TitlePattern } |
    ForEach-Object {
        Write-Verbose "Found update history entry $($_.Title)"
        $SearchResult = $Searcher.Search("UpdateID='$($_.UpdateIdentity.UpdateID)' and RevisionNumber=$($_.UpdateIdentity.RevisionNumber)")
        Write-Verbose "Found $($SearchResult.Updates.Count) update entries"
        if ($SearchResult.Updates.Count -gt 0) {
            $Installer.Updates = $SearchResult.Updates
            $Installer.Uninstall()
            $Installer | Select-Object -Property ResultCode, RebootRequired, Exception
            # result codes: http://technet.microsoft.com/en-us/library/cc720442(WS.10).aspx
        }
    }
}
Invoke-Command -ComputerName $comp -ScriptBlock $scrblock -Credential 'myDomain\administrator'

Instead I get this error

Exception calling "CreateUpdateInstaller" with "0" argument(s): "Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))"
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : ComMethodTargetInvocation
    + PSComputerName        : PC03

Exception calling "QueryHistory" with "2" argument(s): "Exception from HRESULT: 0x80240007"
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : ComMethodTargetInvocation
    + PSComputerName        : PC03

I don't quite understand why the access is denied. Any ideas?

Short answer is that the ComObject does not allow the CreateUpdateInstaller to be called remotely. You can only do this locally, not over sessions or any other remoting. You can however use psexec to remotely execute your script as system.