This sounds incorrect to me.
Withholding taxes are taxes at the source of the income. If a country stipulates that a foreign investor is subject to a 30% withholding tax on dividends, it doesn't matter the tax shelter status of your investment account - That money is never even going to land in your RRSP as it will be withheld at the source. If there is a tax treaty in place, you can apply afterwards to get some of your tax back.
Am I missing a key function here?
Wait, wait, I've seen this one!
Caucasians are too damn tall.