How to capture a variable value in a closure

ScriptPropertyRecalculatesVariable.ps1

function global:Get-CompFolder{
    param($iFolderLoc)

    $objCompFolder = [Ordered]@{
        'Location' = $iFolderLoc
        'Folder' = Get-Item $iFolderLoc
        'SortedTree' = @()
    }
    New-Object -TypeName PSObject -Property $objCompFolder | 
        Add-Member -Passthru -Type ScriptProperty -Name Tree -Value {
            $root = $this.Folder.PSPath
            Get-ChildItem $root -Recurse | % {
                $_ | Add-Member -PassThru -Type NoteProperty -Name RelativeName -Value (
                    "." + $_.PSPath.SubString($root.Length)
                ) 
            } #  No closure, because NoteProperty is calculated at assignment
        } # Closure Not needed, because we get iFolderLoc from $this.Folder
}

ScriptPropertyWithCapturedVariable.ps1

function global:Get-CompFolder{
    param($iFolderLoc)

    $objCompFolder = [Ordered]@{
        'Location' = $iFolderLoc
        'Folder' = Get-Item $iFolderLoc
        'Tree' = Get-ChildItem $iFolderLoc -Recurse |
            Add-Member -MemberType ScriptProperty -Name 'RelativeName' -Force -PassThru -Value {
                "." + $this.FullName -replace ('.*' + [regex]::escape($iFolderLoc))
            }.GetNewClosure()  # Without this, $iFolderLoc won't have a value when this is evaluated later...
        'SortedTree' = @()
    }
    return New-Object -TypeName PSObject -Property $objCompFolder
}