It's probably cheaper and less bureaucratic to mine bitcoin.
There is no infrastructure to build to hook it up to the grid, and no lengthy building permit/environmental permit processes to go through and no power company to negotiate with, etc.
That's not quite the point. Bitcoin mining can easily lose money even with free power and if those gas producers aren't using flare gas e.g. to power the production facility itself then it's likely a lot more complicated than just piping it to a generator.
Anyway, this turned out to be fake news.