If that were the case, you'd have a better managed transition.
Ideally you'd have the CEO onboard with this from the start. Alternatively when it came time to boot them, you'd a) already have someone in place to take over b) be able to pay them off sufficiently to not make a fuss, and help you frame it as transitioning to a new role (i.e. they'd stay on as an advisor, move to a COO role etc.).
Yes, I think throwing out the CEO of an established company with revenue is quite a bit different than throwing out the CEO of a pre-product startup however.
With a startup, you've invested in the founding team. If you throw them out... you've effectively thrown out a significant part of what you invested in. It also calls in to question your own judgement as an investor. And it reduces your standing in the eye of companies looking for investment.
Overall, unless something really really bad happens you don't want to throw out the founder...
If you just don't have confidence? You either let the investment go, or you try and pump it and get someone to buy you out in a subsequent round.
The only possibility I can see if that someone wants to buy Zoox, they made a really generous offer... but the Zoox CEO blocked the sale. Acquiring company is willing to take Zoox without the CEO to get Zoox out of the market, and acquire the team for their own projects...
Ideally yes, likely, no. From the sparse details we do have it sounds like there were some fundamental disagreements between the board and CEO. The board may have seen firing the CEO as the path of least resistance. It seems harsh, but without extensive insider details, it's hard to know whether it was the right call.