I think it's important to avoid saying doing X will reduce warming if it doesn't do that, so that people don't start believing that it will be sufficient to do only this.
The only time I've seen that argument raised is for the opposite "Because this won't fix global warming, we shouldn't do it?".
Global warming will require a multifaceted approach to be solve. No one solution will fix it, so literally any solution is going to have a detractor that says "This won't fix it, so why bother with it?"
Reducing and fixing or eliminating are not the same thing. How could they have worded the title better? "Limiting methane emissions will have an outsized impact given the cost"?
It's also true that increasing global average warming can result in reduced warming and temperatures in some geographic areas so it is important to be specific with terminology depending on which aspect of the climate change debate we're talking about. You are right that the title is unintentionally misleading in this regard.