They follow Cypress laws. They aren't Russian company. Why Russia could seize their servers in Bulgaria?
Maybe Russia would seize MtGox servers in Japan? Or Bitstamp's in Slovenia? All exchanges will fire because of Russian govt! We all will die! PANIC! SELL SELL SELL!!!11
The USA seized servers and arrested Kim DotCom in New Zealand. Even using FBI hardware and officers to do so.
The USA gets UK citizens extradited for breaking US law, despite the fact that the citizen never broke any UK laws.
Powerful countries have leverage over less powerful countries, especially when any kind of trading links are involved.
If Russia is serious about nailing BTC-E for whatever reason, and it leans on Bulgaria to any degree whatsoever, these servers are getting switched off. Simple as that. After all, the Bulgarian government wouldn't want to run the risk of aiding 'terrorists' would they?