The memo sounds like spin because it is. The surface argument is equivalent to arguing that no one could sell closed source software because open source exists, and that open source must also be commodotized (oddly, Apple and Microsoft are doing just fine). The implied argument is that Google Research was doing fine giving away their trade secrets and giving negative value to Google because it was going to happen anyway and the secrets are financially worthless anyhow.
Nonsense. There are moats if one is willing to look for them. After all, productizing is a very different thing from an academic comparison. ChatGPT is way out there _as a product_, while open efforts are at 0% on this. You can't lock down a technology*, but you can lock down an ecosystem, a product or hardware. OpenAI can create an API ecosystem which will be difficult to take down. They can try to make custom hardware to make their models really cheap to run. Monopoly? Nah. This won't happen. But they could make some money - and reduce the value of Google's search monopoly.
* Barring software patents which fortunately aren't yet at play.
EDIT: I'll give the memo a virtual point for identifying Meta (Facebook) as a competitor who could profit by using current OSS efforts. But otherwise it's just spin.