ClosedAI were able to use being "open" to market their start-up. They were able to use that to attract funding / investment. Then, they transitioned away from that with a convenient excuse when it came time to launch their product.
This is the same playbook that Hashicorp and Reddit used. They were "open source".... Until they weren't. Reddit even had an open API... Until they didn't.
Being "open" can also be a way for someone to bootstrap their start-up by bringing on free labor.