So, theoretically, if this was being considered for DHS, it could make some sense over the Door Coaster since... (1) it could potentially be build quicker then the door coaster and (2) it might only require Soundstage 1 more or less as a footprint. Point #2 is important because from what I understand of the Door Coaster plans, the building behind was going to be the entrance, which means that BLT basically needs to be shut down to get onto the Door Coaster. Theoretically, they might be able to get this dark ride up and running with an entrance from the Pixar Place "street" next to TSMM and allow BLT to run for a while longer. Also, if this ride is a smaller footprint compared to the coaster, then it might allow more room for other attractions or whatnot (hypothetically, for example, building the Ratatouille ride and a Gaston's French restaurant).
Just a guess on my part and I'm not talking about any specifics, but I could see how this ride might be perceived to make more sense for DHS than the door coaster.