I don’t think that’s the case at all. Gearbox is developing a mobile game to take advantage of owning the property, along with whatever they plan to do with Risk of Rain 2 now. Returns is from the original studio and is more of a love letter / farewell to the franchise.

Hopoo, the original devs, were already making this and got to finish working on it after the purchase. It adds new content and refines the gameplay of the original (movement feels better and the game just generally plays better) - it was also designed with modding in mind.

This project was an effort by the original developers, not by gearbox.