Preventing companies named [adjective]+[product/service provided] doesn't seem sustainable.

They haven't prevented that. They have prevented trademarking the terms, thus other people whose AI offerings are Open are in fact allowed to describe their products as an Open AI, I presume they are not allowed to describe their products as being OpenAI however as that would create consumer confusion.

Furthermore they have not said anything about [adjective] being non trademarkable, they have said that you shouldn't be able to trademark things that have specific meaning in your industry, as Open has some specific meaning in the software industry.

Thus you would probably be allowed to name your things [big] +[proudct/service provided] or in this case bigAI because big does not really imply a specific desirable quality in the Software industry.

Now before you start talking of how you can see blah blah how big would be useful blah blah, as is the tradition whenever programmers encounter a legal decision that they do not agree with, it just ain't gonna work. I guess though I cannot prevent the inevitable, but nobody in IT says does it have the technical quality of "bigness" before purchasing, but they do about the quality of "Openness", so obviously some adjectives would be untrademarkable in this context, if you named your AI SecureAI probably no go, If you named your AI UglyAssAI probably fine.

This ruling is very early in the process and doesn't prevent anything - but given the more likely bad path outcome of this case for OpenAI it wouldn't disallow their usage of OpenAI but instead prevent them from shutting down competitors that claim to offer an open AI.

Preventing the hijacking and privatization of short phrases and language in general is actually an excellent thing. I applaud this decision, and wish for the rules to become even tighter.

Companies can be named after random nonsense, ‘pink catfish’ could easily be the world’s #1 supplier of firearms and nobody would find it strange.

Caterpillar, Apple, Kellogg, etc really don’t have anything to do with the underlying product but neither do people’s names.

This seems a lot more sustainable than allowing me to trademark a tire company called "WinterTire" and enabling me to sue any other tire company that tries to capitalise on my trademark.

(And if WinterTire Co was anything like OpenAI, it'd be focused on making summer tires)