Even if true, it's odd that Jon Stewart is only complaining about it now.
For one, you would think that all these terms would have been made clear upfront at the time of him signing the contract with Apple. I am not saying it's necessarily okay that a world-spanning tech company has increasing editorial control over our media ecosystem, but I imagine he would have been made aware of what topics are okay to cover (and which are off-limits) right from the start. So why agree to Apple's terms, knowing fully well that China was not to be touch, only to gripe about it a year later like you have been living in the matrix all along and have only just woken up?
As such, it seems more likely that his show wasn't renewed due to poor ratings, and not just because it was apparently less compelling than his previous daily show, but because a talk show seems more suited to linear TV. I turn on my TV set at a prescribed timing and it's there, because that's what filler content on linear TV is supposed to do - fill a time slot.
In contrast, I would argue that for a streaming network, you want evergreen content without an expiration date that someone can search for months, even years later and it's still relevant.
The entire concept of a talk show on a streaming network just seems flawed to me, and I won't be surprised if we see less (or even none of them) on TV+ moving forward. It's not so much that it may touch on sensitive issues that may pose a PR issue for Apple, but more that news, by its very nature, has too short an expiry date to justify being on one.