It is terrible tactics, similar to the Egyptian government decision to shut down the Internet. The latter was the best thing the government could do to build the protests. Once the Internet went out, the only way to find out what was going on was to shut off the computer and go out into the street. It was also seen as proof positive that the Government was weak and on the brink of collapse.
The government is widely considered to be illegitimate, having stolen the 2010 Presidential election with a rules change during the election designed to make fraud easier. The former Prime Minister is currently in jail on trumped up charges. Such a government can only rule by intimidation. The last parliamentary election was in 2007 and it is unclear if there will be another.
But the key to intimidation is to pick off a few people at a time, make an example of them and go on to the next batch. Telling everyone that they have been registered as a dissident and should report to the gulags for incarceration and murder gives the game away too soon. The government has just told the opposition that they have nothing to lose.
There will also be a lot of children of politicians caught up in those sweeps. And that could well prove decisive. Ukraine has a parliamentary system (for now) and a revolt by MPs can bring down the government.