If the airdrop had taken place I think Dash would have been way ahead of where it is now in terms of marketcap and support from the community in general.
The only thing the airdrop would have done is diluted the instamine by another 2 million coins. So it would be about 25% of the current supply instead of 33%. And then it would have added questions about who actually got those airdrop coins and how they got them. In the case of the Stellar airdrop for example, there are published allegations of massive fraud by insiders.