“How can he not see what he wants to see?”
The 4th Amendment.
IF one president can seal and unseal various things, a future president can unseal and look at what the former president did.
There are no restrictions on the president that way.
The president does not need a search warrant to view what a prior president has done.
It would seem to me, there is a difference between “opening for public use and possible prosecution” (my interpretation of the 4th amendment coverage) and opening sealed records for a president to look at them.
Sure Obama may be immune from prosecution, but I think Trump could look at whatever he decides to look at.
Not an expert however. Others may have more educated responses, but it seems to me, he can look at what he wants to look at.