A forgery won’t work. There are too many people involved who know the truth, and so many other records - hundreds or more - that also have to be forged, and indexes of those records, and copies in various locations, and on and on and on. That’s why every single paper from his entire life is off limits.
Plus records from other countries, passports, etc.
There is no way all of that can be forged. One forged birth certificate will be discovered to be forged by a high school researcher, if one should show up.