Does it protect sensitive events?
Moving or cancelling a calendar entry, or inviting anyone to one, always requires your approval. Before the assistant moves or cancels anything on your calendar, or sends an invitation, it shows you what it proposes and waits — that is enforced in the system itself, not left to the assistant's judgement. The one thing it does directly when you ask is create an event only you attend, and it tells you exactly what it created. When it isn't sure whether something is sensitive, it surfaces the decision to you rather than guessing.
It does not change an event's visibility. Whether an entry is public, private, or default in Google Calendar stays exactly as you set it — Lonzo reads that setting and never writes it. If you want an entry marked private, set it in Google Calendar.
On the Agenda plan, Lonzo never contacts anyone else about your calendar, so nothing is disclosed to a third party for you to have to protect. Setting up a meeting with other people — Lonzo does not reach out to the participants for you on this plan; that belongs to the Assistant plan, and it isn't part of the current release on any plan. Today a meeting you ask for is recorded for you and nothing is sent to anyone.
See also: How does it keep things confidential? · What does it ask before doing?