I've heard people argue that its both too aggressive and too conservative. I'm in the too conservative camp, we need to figure things out sooner than 100 years and the risk of a feedback loop is high with methane.
Its fine to assert that a single number doesn't capture the nuances of the situation. But we have to keep in mind that
1) the heat trapped by the methane stays trapped even after it has decayed
2) methane concentrations in the atmosphere are increasing significantly faster than co2
3) the more methane in the atmosphere the slower its rate of decay