Why should they?
Because Trump told them to release "any and all other information".
"In a post on his social media platform Thursday night, Trump said he was directing government agencies to release files related “to alien and extraterrestrial life, unidentified aerial phenomena (UAP), and unidentified flying objects (UFOs), and any and all other information connected to these highly complex, but extremely interesting and important, matters.”"
Trump says he doesn’t know if aliens are real but directs government to release files on UFOs, more