Why this fear?
The second reason is the insensible freedom "Freedom of speech". The US speaks of it highly but it doesn't practise it. In the US, there are laws of defamation and you can't speak against democracy. By this they mean freedom to speak against Islam which doesn't hamper their interest. Bangladesh is no different. The government is allowing some people to speak against religion freely and also the fanatics to issue death threats. It's only natural for uneducated mullahs to get excited. So "Freedom of speech" should be specified by DOs and DON'Ts .
Finally, I don't understand why some people are trying to relate Hizb-ut-Tahrir with Islamic zealots. The members of HT are well educated students and professionals. Also they use modern technology effectively. They conduct all their programmes openly. The old habit of "doubting everybody for one" seems to reign supreme.