Difficulty is not a criterion for closure.
You'll notice that when you vote to close or flag for "needs improvement", "question is too difficult" is not one of the reasons offered. Our site is one of the better places on the internet to ask difficult questions. We have lots of experts in lots of different games. Answering difficult questions is one of the things we're good at.
This question has many of the key features of a good optimization question.
Now, about this specific question, I will admit, I am not an expert in D&D 3.5e. However, I do have a bit of experience on the site, and it seems to me that this question has several of the key features of a good optimization question. Reading through, the question provides:
- Campaign setting details
- Ground rules for building the item
- Relevant rules in place at the table
- Character build details
- Permitted and non-permitted sourcebooks
- A first attempt at optimization ("show your work")
- Areas where that first attempt might be improved
Overall, this question provides extensive background details, expectations for the build, rules for the table and setting, and even a first attempt that answers may use as a starting point. This question provides far more detail than we typically see from optimization questions, and its objectives seem clear enough to me. I think the question is fine. But of course, I should hedge this with the reminder than I am not a 3.5e expert, so I may be missing crucial system knowledge that invalidates my analysis here, so keep that in mind.