Youtube page, which has auto-generated transcripts: https://www.youtube.com/watch?v=lLEkUGuw374

tl;dw:

1. it's expensive

2. requires online connection and account to unlock bootloader

3. lenovo (the parent company) had shady behavior in the past

Summary:

- The Motorola flagship costs too much and he's worried it will no longer run on the Pixel 7a that he got for $200 or that there will be any cheap options.

But they said already there would be cheap options, and Motorola has a Moto G series that it would likely use.

- Worried about other stuff that existing Motorola Android phones do, like privacy violations.

...that definitely won't be in GrapheneOS, they wouldn't allow it.

- More things Motorola does as a company that are bad.

The current option being Google means, despite that, Motorola is probably better.

tl;dr:

- GrapheneOS is only supported on Motorola's flagship devices, which the author deems too expensive

- Motorola historically has made unlocking the bootloader difficult, and GrapheneOS has not yet confirmed that this will become easier.

- The author does not trust Motorola.

Last time a custom Android distro (CyanogenMod) made a deal with a manufacturer, everything went belly-up. I have little faith that the same won't happen again. :-(