Individuals whose abilities change over time can benefit from assistive technologies that can detect and adapt to their current needs. While these Adaptive Assistive Technologies (AATs) offer exciting opportunities, their use presents an often-overlooked privacy tradeoff between usability and disclosing ability data. To explore this tradeoff from end-user perspectives, we developed a participatory activities toolkit comprised of tangible low-fidelity physical cards, charts, and two software AAT prototypes. We used the kit in interviews with six older adults who experience pointing and typing difficulties when accessing the Internet. Participants had conflicting views about AATs collecting their data, and strong preferences about what data should be collected, how should it be used, and who should have access to it. The contributions of this paper are twofold: (1) we describe a novel approach to elicit detailed end-user privacy preferences and expectations, and (2) we provide insights from representative users of AATs towards their privacy.