In its neverending concern for the public welfare, I'm sure the company could see no good to come from causing worry, concern and panic. Additionally, a panicked public could cause the stock price to drop as the company decided to spend some money on efforts to minimize the leak.

Any effort which would be rapidly effective would cost a small fortune. The gas is invisible, and the PR people have managed to keep public outrage to a minimum, and no birds are floating around with tar all over them there is no reason to take the matter seriously.

Saner heads realize there is a finite amount of methane in the ground. It will cease leaking eventually no matter what efforts are made, so there really isn't much sense in spending the limited resources of the company.