Well, the rebels don’t have helicopters. Aside from the ludicrous assmuption that they would bomb themselves.
Of course they have incentive to bomb themselves - a false-flag in order to prompt outside intervention on their behalf. This is a complex war with many sides, and we have to think cynically about the motivations of all the different “actors” here.
Unless there is solid, independent intelligence to establish what actually happened it is premature to start more violence. After all, collateral damage from US intervention in the area has killed hundreds of civilians, children included. The goal should be less bombing, not more.
The Turks have helicopters. And gas, etc. It could be a black flag op by them to get rid of Assad. Erdogan is making his move. I have no basis for saying this, but I doubt very seriously that the rebels did it themselves. Erdogan met with Putin and Rouhani last Wednesday and then this gas attack happens. Any connection? Might they have decided to let the West get rid of Assad and then divide up the spoils?