Older adults are most often considered consumers of online information, but recent work highlights the importance of engaging older adults in content generation and online sharing. One context in which older adults generate and share content is art therapy for individuals with dementia. Our analysis draws on Altman's notion of privacy and territorial regions to understand what sharing means for this vulnerable population. This theoretical framing reveals the ways in which privacy is cooperatively negotiated, which is in contrast to the individualistic view of existing sharing systems; how older adults derive benefits from sharing depending on interaction with their audience; and how sharing fluctuates between a focus on the process of therapy versus the product depending on privacy needs. Our analysis contributes an understanding of the complex nature of sharing for vulnerable populations and offers design considerations for systems that support this practice.