His wife can certainly petition for him but it will still be immensely difficult to obtain a waiver of the 10-year ban. The reason is that the marriage would occur after your friend had left the U.S. as unmarried. The immigration agency, USCIS, would find it hard to believe that the wife was now facing "extreme hardship" just because her husband isn't with her when in fact he wasn't with her ever, namely they weren't married before.
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I am not an immigration attorney nor do I have any experience litigating immigration cases. As always, seek professional advice before pursuing any course of action. I cannot be held accountable for any consequences of my comments.