Today, we are launching Proton Sentinel, a high-security program that will allow our teams and systems to better protect users who need the most security. This program was motivated by our years of experience serving high-profile people and organizations from around the world. Some of our most security-demanding users include journalists from the largest publications, governments of several countries, leaders of international peace organizations, heads of major religions, and members of parliaments. Accounts such as these have a high risk of being attacked by criminals or state-backed hackers. We are now ready to provide the same level of advanced protection and support that we reserved for these VIPs to any Proton user that wants it through the Proton Sentinel program.
Link to Proton's blog post: https://proton.me/blog/sentinel-high-security-program
I wonder, so why not just force Sentinel program users to enable 2FA?