From my understanding, you are correct.
This is something they have done multiple times in the past. Some examples are “Friendly Faces” had a pilot trial, but then when it officially launched, it was limited to Cam Protect when it launched. Same thing for Smart Vision or what was called Wyze Anything Recognition. That also had a pilot trial, and then with the Cam Protect launch, it was limited to people who got Cam Protect. Now Friendly faces has been extended to Cam Unlimited users, but it didn’t use to be. Just pointing out that these trials for other subscriptions are things they have commonly done in the past. I just think they needed to be more clear about it in this forum post, even though they were clear about it in the emails they sent out, because there are plenty of people who don’t read the emails and may have only read about it here in this post.
That would be great. They have done similar things in the past with some pilot trials (Friendly faces for example stayed white-listed for anyone on Cam Plus who joined the pilot program even when it was restricted to Cam Protect, though only for a couple of camera models that were initially allowed during the pilot), though this AI search one probably has a much higher cost than some of the past trials they have done, so I would not be surprised if it ends since the last public beta trial for the AI Video search was also terminated, and they sent out an email letting us know that trial ended. I was in that public beta trial too, and they told us it would be ending and sent out an email when it did end:
I expect this trial will work the exact same way as the last public trial…and nobody was upset when that one ended, though I think they should’ve been more clear in this forum post that this trial was going to work the same way as the lasts one (eventually the trial will end again).
But @WyzeMatt or Jason or someone may always correct me otherwise with new information later. 
I’d love to be wrong and keep this on Cam Unlimited.
However, in multiple places, their public documentation has for months (since way back in Spring time) been saying the AI search would be limited to Cam Unlimited Pro:
So, I suspect this is just a pilot “trial” similar to the last trial that only lasted 2 months before it was also removed from our access. It’s fun to see how it is evolving. I think I am pretty likely to subscribe to the Unlimited Pro when it launches. I’m guessing that is part of what they are hoping by offering the trial…give us a chance to see if we like it and want to upgrade whenever they launch it. If they didn’t let some of us try it out in advance, it might be harder to know if we like some of the new features like this. If they let me keep it on unlimited, I might decide not to upgrade. 
I’m guessing they’ll realize that too.