Yes, indeed, that makes it even more distressing that they didn't bother to license even the core of the system with the GPL. It sends a signal that they really completely don't care about the freedom for users to modify the software and run it on their own hardware.
Why license the kernel GPL if it doesn't matter any because every vendor would be totally willing to put it up in any case (or defer to the official repo because they made no changes anyway)?
Such an approach smells of virtue signalling, and IMNSHO we have way too much of that already.
the "users" of fuchsia most likely will not be developers only, if GPL is just a symbol, a golden star to show you are a good kid then it does not look so foundamental to me.
as other have said the driver API should actually make that easier (in intents).