> Weird to release 1.0 without it. What are they waiting for?

Hmm, I've been under the impression that at one point they said it'd be 100% FOSS by the time 1.0 hits, but maybe I misunderstand/misremember the details. But I remember they'd said it'd be FOSS in connection with 1.0, seems weird to do it this way instead of waiting until it's all FOSS then cut 1.0.

This exactly. Doesn't scream confidence that its still closed upon release.

People to tune in to the conference, probably.

I think they are waiting for a wild success in adoption, and if that doesn't happen they can use the IP to pivot to something else without giving the core away to anyone for free/as open-source.

A lot of people beg to differ. And it's their decision, not yours on when to open source. They have their reasons even if they aren't explaining them to you.