Constructive criticism is very important to any type of collaborative work. The key here is collaboration - and it must be based in fact and reason. That is not an unreasonable standard. Once criticism becomes completely negative and mixed with personality issues (regardless of intent), any real kind of progress becomes impossible to attain.

The best position to take in that case is to focus on the work and get on with it. Even epic trolls will get responses, but there are severe limits to those responses if the situation does not improve. If the project got bogged down in all the attacks, everyone would still be waiting for the first announcement to come out. That's why there is a standard to uphold and to operate in that framework so work can get done and everyone can move forward together.