I think there's more to it than just that. I imagine that Hasbro see the soundtrack as a very niche product. If we consider that fans make up 20-30% of their total market and that the G1 Cartoon and 1986 movie are more of a cult following based item compared to say, the live action movies, it's quite possible that Hasbro and Enjoy the Toons think that there isn't enough demand to support a mainstream release. Considering that Sony are a party in the production, the fact that this isn't being released under sony's main label, also suggests this is the case.
As such, it could be that Hasbro are deliberately creating scarcity to drive demand, ensuring that it's a success by gaming the market.
Two problems I see here. The first is that you'd automatically be dumping 3 times the amount of stock on the market and in doing so, destroying the sense of scarcity which then lowers demand, harming the success of the release. The other thing is, given that the company now pushes the "premuim audiophile vinyl" angle as a brand image, there's a change that this could be seen as a harmful PR move to the company.