So, what some honest miner(s) can do to help the coin to survive the attack? Mining trc using official client or may be there is some more effective way?
It appears the time lapse attack is more of a bug in the code of terracoin, and would need fixed to prevent this from happening again. There isn't enough legitimate hash power on TRC to just force the attackers out if they are really using 1.2TH or more. Coinotron is by far the biggest pool and only runs about 1/3 that speed typically.