Maybe aliens are bullish on Earth and decided to ape in. If they wanted to actually make contact though, they'd probably just drop a smart contract on the blockchain instead of flying around randomly at night, iykyk.
Servers of blockchain will still be centralized, even if they're not they're seizeable (Hilary's example...
if you know) - Even if aliens did reveal, a news from media to sway away the percention is what it all will take, before you consider them threat.
Anyway, even if you want to contact them, or meet you certainly won't understand what they say, unless you understand their lanaguge, and certainly they won't use steering wheel to travel galaxies.
You didn't hear it from me, but some survivor of some World War did say, 'We will go to war with aliens'...
(Google won't tell you that.)