They take the mathematicians meaning. Open does not mean not closed.
I hope their api pricing goes down over time.
It depends on how many competitors will enter the market. At current stage, I would say the chance of them to increase the price is high. The current price is so cheap, it might as well work for a saturated market, which is not what the actual market is currently at.
I guess their current pricing is designed to attract new users to bring use cases/ideas to them, which would be a field where their the imagination is lacking.
On the other hand, if they ended up chooses a different route, go patented everything and starts suing, then maybe it's better off for them to remove "Open" in their title just to make things more clear.