That's what the court said which I agree with. But what the OSI is saying was the intent of the FSF and what the court case was about is very different.
The OSI, FSF and what the court case was trying to argue was that if Alice publishes something under AGPL with an additional clause. Charlie gets a copy from Alice, and decides to remove all additional clauses and to ignore them, then it is okay because the AGPL says that all additional clauses can be removed.
The judge said that this doesn't apply to the original licensor, that the original licensor can choose the terms of their own copyright, so if they want AGPL + additional clause then those additional clauses can't be ignored or removed. Only additional clause added by licensees can be removed due to the original terms they agreed too when using an AGPL library.
The OSI, FSF and what the court case was trying to argue was that if Alice publishes something under AGPL with an additional clause. Charlie gets a copy from Alice, and decides to remove all additional clauses and to ignore them, then it is okay because the AGPL says that all additional clauses can be removed.
The judge said that this doesn't apply to the original licensor, that the original licensor can choose the terms of their own copyright, so if they want AGPL + additional clause then those additional clauses can't be ignored or removed. Only additional clause added by licensees can be removed due to the original terms they agreed too when using an AGPL library.