system
Given the following post, respond as if you're commenting on Reddit:
human
[Animorphs] Could the Andalites just tell all the humans what's going on?

Could an Andalite ship fly near the Earth and broadcast a message across TV signals or something, telling humanity about the war and the Yeerks slowly taking them over? 

I realize not everyone would believe them, and there would be tons of debate over whether humans could trust these random blue aliens, but just putting the information out there would at least sew doubt. Enough people would believe them to start a real investigation, which might lead to significant resistance. The Yeerk operations on Earth might at least become more difficult if the humans were given some kind of clue of their existence and what they're up to.
gpt
The problem is, it'd just turn it from a cold war into a hot one.  Earth would become a bloody, burning battlefield.  There'd be intense mistrust of each other by every human, it'd be very difficult to organize any sort of defense when everybody else could be affected.  Not to mention that we'd be caught between two warring space superpowers.  All the F-16s and aircraft carriers we have couldn't take down one of their starships.