TLDR edit: I'm supporting the above comment - ie. i do not support apple's actions in this case.

It's definitely good for people to learn a bit about homomorphic computing, and let's give some credit to apple for investing in this area of technology.

That said:

1. Encryption in the majority of cases doesn't actually buy absolute privacy or security, it buys time - see NIST's criteria of ≥30 years for AES. It will almost certainly be crackable either by weakening or other advances.. How many people are truly able to give genuine informed consent in that context?

2. Encrypting something doesn't always work out as planned, see example:

"DON'T WORRY BRO, ITS TOTALLY SAFE, IT'S ENCRYPTED!!"

Source

Yes Apple is surely capable enough to avoid simple, documented, mistakes such as above, but it's also quite likely some mistake will be made. And we note, apple are also extremely likely capable of engineering leaks and concealing it or making it appear accidental (or even if truly accidental, leveraging it later on).

Whether they'd take the risk, whether their (un)official internal policy would support or reject that is ofc for the realm of speculation.

That they'd have the technical capability to do so isn't at all unlikely. Same goes for a capable entity with access to apple infrastructure.

3. The fact they've chosen to act questionably regarding user's ability to meaningfully consent, or even consent at all(!), suggests there may be some issues with assuming good faith on their part.