I don't think it necessarily means Widmore is a good guy. I think it is just a plan for war -turn off toxic gas so Ben doesn't use it against me. Ben's people probably turned it on - was Ben really going to kill everyone on the island? Including all the people heading for the temple (including that dreamy Richard Alpert?) Or is the "temple" some kind of bomb shelter that would have protected them in the event that gas was released on the island?

__________________