Yeah, no, guys. Lidiyaden is correct. You can not add a contact photo to contacts which are stored solely on your SIM. You have to either move them to your device or store them in your Google Contacts. If you click "Edit" on one of your SIM contacts, it will only show a name, number and email field, with no camera icon or other options. If you select a photo from your Gallery and click "Set as contact picture," you will be presented with your contact list, which will exclude any contacts not saved to Google or device storage.
I gave up after weeks of searching for a viable solution. Thanks, Lidiyaden.