It is more than just briefs. Amici curiae means 'friends of the court'. They are only permitted either by consent of all the actual parties or upon application if the court decides that the prospective amici offers a unique legal perspective. The parties to the litigation are given wide discretion to call witnesses, so you don't need to be an amici for that, just subpoenaed and tendered.

Encode successfully navigated this, by not offering facts (who did what, and when), since they don't have any first-hand knowledge of the facts. What they offered, according to their brief (which is attached as a sechedule to the "main document" for document 72), was their philosophical and technical perspective, particularly as a public body concerned with AI safety vis a vis the change in structure of OpenAI.

If you read through the two proposed briefs, they are night and day. Encode describes the interest that the public might have in OpenAI continuing under its present structure, compared to transitioning to a for-profit enterprise, the risk of AI, and why it should be avoided. The employee brief recounts meetings,  memos, and who was making promises.

In a very abstract way, Encode is basically saying that the transition shouldn't proceed because it would be bad for society and humanity. This is a perspective that isn't captured by either Musk or OpenAi/Microsoft. The employees tried to say that OpenAI and Altman made promises to them, and those promises should be kept, which is almost entirely factual. What little non-factual element might remain in the employee brief is essentially in line with Musk's argument, so they offer nothing unique that would assist the court.

The request to file the amicus brief was denied because the court (rightly) interpreted the content of the brief as purely factual. Without consent of all parties, amici curiae are normally only granted when they are able to offer a unique legal perspective on the matters in dispute between the parties. Going through the proposed brief, it seems that nearly all of the substantive content is factual, being descriptions of processes, statements, and general history. Plainly speaking, this is just inappropriate and has rightly been dismissed.

If Elon wanted these facts to go in, he could have contacted these employees ahead of time and had them provide evidence directly. The employees don't get to perform an end-run around the rules of evidence by putting all of their factual assertions into a brief.

With respect to your question about the request for judicial notice, the Order refers to the filing that had requested that relief (document 104), and the documents that they were requesting the Court to take notice of were the following:

1. A true and correct copy of the complaint filed on February 29, 2024 in the case captioned Musk v. Altman, et al., Case No. CGC-24-612746 (S.F. Sup. Ct.), attached as Ex. A to the Wiener Declaration;
2. A true and correct copy of the request for dismissal filed on June 11, 2024 in the case captioned Musk v. Altman, et al., Case No. CGC-24-612746 (S.F. Sup. Ct.), attached as Ex. B to the Wiener Declaration; and
3. A true and correct copy of the opposition to demurrer filed on April 10, 2024 in the case captioned Musk v. Altman, et al., Case No. CGC-24-612746 (S.F. Sup. Ct.), attached as Ex. C to the Wiener Declaration.

These documents are the first lawsuit that Elon filed and then discontinued, and have nothing to do with the charter.