Personally, I hate that gas. It's more of a hindrance than a help. From what I've been told the guy that activates it gets credit for killing the enemy team but when it's been used on me I've never died from it. So I have to wonder if it serves any purpose other than to make everyone's life more difficult. Perhaps that's why it comes up as sabotage? Maybe it just means that everyone is now screwed. That is unless you have a tracker sight or a thermal that you can pull out.
It seems to cause a chain of explosions in the lower maintenance tunnel. I sometimes get 1 or 2 kills with it, i think the gas itself is a secondary effect.
There are also some areas that explode on the main floor as well (and if memory from a recent match serves, at least one in the two-story central building).
The crate reward is "Sabotage" though, since they use the same icon for all the special crate rewards tied to the related maps. The announcer calling out the specific name is just to warn the players, as is done with most other streak rewards that have map-wide effects.
EDIT: In regards to the OP's comment about not liking to use it because of the even-sided effect, take a class with a thermal-sighted weapon as one of your loadouts, then switch to it before you call the gas in. Now you can see through it like it's a smoke tactical and other players are still disadvantaged. (I think the tracker sight works too, but I don't use that by principle).
They really did miss out on a cool way to make gameplay interesting, though. Imagine that the player who called in the gas gets another streak drop that gives "gas masks" and works like the ballistic vest. After filling up the meter to pick the mask up, you go through an animation to put it on, and now you see better (but not normally). Damage you take cracks the mask and makes it less effective at helping your sight, and won't 'heal' like you do. Masks persist through respawns, enemies can pick them up (or destroy them like any other streak reward), and once the gas is gone you keep the mask on until your next respawn, where it just isn't on your face anymore.