While its certainly plausible that Apple engaged in some kind of two-faced corporate espionage here, another plausible explanation is that Apple is an enormous company, and the part of it that was working on Sidecar had little or no connection at all with the part that was talking to Astropad.
It probably isn't even that. The "Left hand" could be engineers who are only thinking about technical and product design aspects and really want the thing to go off and succeed. And then, just when it's about to happen, a legal team does the final check and someone higher in the hierarchy has to approve it and they say "wait, can we just build this in house much cheaper". The Right Hand just learned what the Left Hand was up to, and decided that it isn't perfectly in company's interest, so they adjust it a bit.
Is there utility in such a distinction?
e.g. if malice, then sharing ideas is more dangerous; if byzantine organization dynamics, then it's less dangerous.
Unless they divulged some really clever low-latency video compression optimizations during these meetings (I bet making the mouse cursor move with low latency was the #1 priority - everything else is boring plumbing)... I'm filing this under the "CEO's slightly dramatically exaggerated regrets", maybe for the benefits of his investors.
But part of the problem is probably the drawing software too, because even native drawing has different latency between drawing apps:
https://www.youtube.com/watch?v=zNbvYaO0ZZ0
It's not an easy problem because even 1 ms latency is noticeable in drawing as Microsoft research showed:
The business reality is that almost any software can be easily replicated by BigTechCo for a max of a couple million dollars, far less than any founder is hoping to get acquired for.
In an acquisition, buyers are not buying the software despite whatever PR-friendly face gets put on it. They're buying something they can't just easily generate by locking a few of their already-employed engineers in a closet, which means either a) intellectual property via patents; or b) an audience/userbase that the acquiring company can't already easily access.
No entrepreneur should go into it without internalizing and understanding that. Code is cheap. If you want to be acquired, you have to bring something to the table.
(also note: for Google and Apple, "a lot of mobile users" isn't really part of that equation)
Holy crap they got (HBO) Silicon Valley "Brain Raped."[0] What sickens me is that Apple wouldnt just outright buy them out instead. If you are designing something like this... Make sure you patent as much as possible. That would of guaranteed a buyout. Course not sure how patentable that idea would of been by now if they had other competitors.
[0]: https://youtube.com/watch?v=JlwwVuSUUfc