It's a step, though. Methane is inherently unstable and won't stick around in the atmosphere forever once we stop emitting it. CO2 gets absorbed into the ocean very slowly and with acidification as a consequence.

It's important to say explicitly what "not forever" is here. Half life of methane in the atmosphere is 9 years[0]. Then it decomposes into CO₂ and water; the latter is suspected to be a potent greenhouse gas at that altitude[1].

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[0] - https://en.wikipedia.org/wiki/Atmospheric_methane#cite_ref-C...

[1] - https://en.wikipedia.org/wiki/Atmospheric_methane#Atmospheri...

But in the meantime methane has bigger effect (per kg) than CO2.

Good point. CO2 equivalents are a better measure than CO2.

I think fixing leaks is an easier task than reducing the coal CO2 footprint. We'll have to figure this out somehow anyways, because a lot of methane will be going into the atmosphere from thawing permafrost, both on land and in the seas.

It's not easier - as I understand it, the leaks are tiny amounts along the entire length of the pipelines. Getting an absolutely perfect seal is something that's expensive to do, whereas in theory the CO2 footprint of coal is concentrated and therefore much easier to capture.

In practice, doing either of those will spike the price of the energy, and the only reason to use them over renewables is their being cheap, so it won't happen.