The two people in the group with radioactive clothing worked in a nuclear facility. As another commenter pointed out, the YT channel Lemmino made an excellent

The two people in the group with radioactive clothing worked in a nuclear facility. As another commenter pointed out, the YT channel Lemmino made an excellent video with research based on the primary sources, and the conclusion is, unsurprisingly, not aliens. When all the facts are considered, the whole incident is probably only still considered mysterious because it makes a better story.