TL;DR: no bug here, that's how imgur works. You're NOT using Gravatar, at least not in your Stack Exchange accounts.
When editing your profile, you uploaded the image, by this making SE use imgur to host your avatar. As it stands, imgur does not support 96x96 size (which is used in the Users page) for the images it hosts (at least not in the dedicated Stack Exchange service) so it serves the full image instead.
If you want to use Gravatar you have to edit your profile, click "change picture" and choose Gravatar.
Also worth to note, I have no idea what you mean by "user chose to crop", never seen such thing, and surely it's not something imgur supports. The image you uploaded is not cropped in any way. It's showing as "cropped" in most places because imgur must resize it and "crop" it when generating the thumbnails for the set of sizes it does support. But you can't choose anywhere how it will be cropped.