The IMAX aspect ratio was 1.44:1. It’s impossible to crop a 2.35:1 footage to 1.44:1. Do you realise how ridiculous the shot would look?
Is it possible that the entire IMAX scene was not in 1.44:1/1.90:1 (LIEMAX)? Maybe this BB8 shot was in 2.35:1, but it was so short and it was a fast scene that you didn’t notice the aspect ratio shift? I mean I’ve read in many forums that people failed to notice aspect ratio shifts on fast shots of partially IMAX filmed movies.
Even if this shot was in Full/half IMAX, I doubt it was a cropped shot. Because a zoom-in of a scope shot would look too big and bad on a giant screen.

I think, if you plan on doing a final version, please at least consider using the uncropped anamorphic shots. Those BB8 shots were done with 2.35:1 locked shots. There’s virtually no information left on the top and bottom. So, there is no way those shots could be opened up on an IMAX scene. The texture of those shots look very much like ones from anamorphic lenses. There is more grain, which won’t be the case with the IMAX scenes in the first place.