It really depends how much of the methane in the entire chain is combusted. Uncombusted methane has a short term radiative forcing 100x as much as C02.

And it turns out there are a lot of leaks and incomplete combustion in the overall methane supply chain. Residential hookups are a significant source of slow leaks.

So completely avoiding a hookup in the first place may have a larger climate impact than your napkin math suggests.