Sergey Brin doesn't have a Twitter account
(and never had one)

All the accounts you see on Google don't belong to Sergey Brin co-founder of Google.
Sergey doesn't have any social media accounts. No FB, no YouTube, no Instagram, no official website, no nothing
If you're interested in Sergey's thoughts - watch his interviews on youtube:
https://www.youtube.com/results?search_query=sergey+brin