The additional point he's trying to make is that app developers should use FLAG_SECURE if its confidential data - messaging probably should be, and his bitcoin app should almost certainly be.
It is one thing to block automatic screenshots or screen recordings. Another when the user explicitly tries to take a screenshot.
It's on by default, which should be true for most apps with confidential data. But other apps (like photos and messaging apps, can at least have that as an option defaulted to false, for users who would like the extra privacy)
Your conversations aren't nearly as sensitive to require such a large breach of usability.
Yours might not be, but this isn’t true for everyone.
Because your sentence just sounds like platitude without any thought behind it.
The flag should secure it from other apps but the user screenshot tool should be able to override it. The cap framework should be able to do this, you just need to insulate the app itself to ensure only real people can use it.