Complex sentence: These reports were dismissed by UFO proponents as being either disinformation or simply implausible, while several high-profile UFO researchers discounted the possibility that the incident had anything to do with aliens.
Split into simpler sentences: These reports were dismissed by UFO proponents as being either disinformation or simply implausible. But at the same time, several high-profile UFO researchers discounted the possibility that the incident had anything to do with aliens.