There is also the current opinion of Steam Early Access to consider. It seems a lot of people have issues with SEA and neither do research or notice the blue box telling them taht the game is in Steam Early Access, and what that entails.
Word of mouth is a powerful thing, even if it is spread by a loud minority made up of complete idiots that can't be bothered to read more than titles.
Incentivising these people to buy the game via a sale before it is completed might be a bad idea, even if it means Goldhawk miss out on legit productive community members.
(Besides I personally wonder how involved people that wait to buy a game on a sale will be in it's community)