I have two accounts, one is my main account with all my games on it.
And the other which I use for non-suspicious CSGO uses.
At the time when the Alpha was released I was playing CSGO and activated it on that account.
Is it possible to transfer it over to my main account or will forever been stuck I’m my alt?
Might it be worth getting in touch with the Steam support? I’m not certain of any official policies or case-by-case decisions, but if they can verify you are the owner of both accounts they might be able to move it across manually.
They won’t do it. It’s unfortunate but just Steam Family Share it across. The reason it won’t work at the moment is because the game is not released in the Store. Once it is you will be able to play on your main.