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He will confirm that there are unexplained phenomena, and that there is an agency committed to their study. He will not confirm that alien life definitively exists, but he won't rule it out, either. People who believe will feel vindicated, and people who do not believe will be underwhelmed.
Time is a flat circle. Scientists won't ever rule anything out completely, and unexplained phenomena are worthy of study. Of course UAP's get documented, and of course money is spent on it. Of course it is kept secret, because quite often those flying craft are terrestrial spy vehicles and drones, and we don't want to share what we have or what we know.
I was surprised to hear someone admit that people have been killed to keep secrets, but I am not surprised that people have been killed to keep secrets.
All of that can be true even if aliens have not visited our planet. If they have, and we have proof of it, that will not be included in the NASA report, or any other testimony.