It’s absolutely not hearsay. There are recordings of everything which was said over the radios, there are recordings of every radar contact, everything each of the CIC consoles were displaying, there are recordings of all the data that was being transmitted over the various comm/data links (11, 4A and 13). Every bit of the data from these encounters which were observed/detected by navy sensors are recorded so what the pilots, radar operators etc...etc... say happened is not hearsay, everything they say is backed up by data recordings.
Which predictor of the future was it who recently said we are about to find out our entire world has changed forever? One of those guys who make videos that are no longer allowed on YouTube.