Yes, it's open source. I wouldn't try to claim it isn't, like the parent is doing. However Google being behind it still makes me nervous, specially since this might end up replacing the copyleft Linux kernel and contributing to furthering the locking-down and tivoization of Android.
I do not understand what this means, the code is open isn't it?[0]
This sounds very over exaggerated and alarmist, just like Android and for example Chromium people have forked it and removed all the Google proprietary stuff from it[1], I am sure you and other privacy conscious developers in the future will do the same for Fuchsia.
[0] https://fuchsia.dev/fuchsia-src/development/source_code
[1] https://github.com/Eloston/ungoogled-chromium