I just took a look at the Ukrainian local thread and there is very little activity there.

Because all activity of UA-users expressed as a political offtop in crypto topics.

https://bitcointalk.org/index.php?topic=2235093
https://bitcointalk.org/index.php?topic=1006631
https://bitcointalk.org/index.php?topic=5216108

Why nobody stopping these political offtop?

Even politics section is not active in politics like these above topics. Because our politics section is a most boring place in the forum. But rubbish crypto-threads is very active in politics because there many opinions intersects