The previous review of this episode by planktonrules says that McGarrett's botched plan caused one more officer to be taken hostage and one to be killed. Truck and the other officer volunteered to try and drop that knockout gas on Karl. Steve didn't tell them to do so and was apprehensive about sending them. It wasn't Steve's plan.
The governor took the blame for that incident, and Steve told him he wanted to proceed with his original plan.
McGarrett made mistakes in many earlier episodes, but seeing him make mistakes does not bode well for the show when it causes the bad guys to keep operating, and if he kept making mistakes all the time, he would get no results and we would have no show.
Also, remember that these characters taken hostage or killed were police officers who knew that when they took on this job, there was risk involved, and they could not deal with these terrorists without someone getting injured or killed.
The governor took the blame for that incident, and Steve told him he wanted to proceed with his original plan.
McGarrett made mistakes in many earlier episodes, but seeing him make mistakes does not bode well for the show when it causes the bad guys to keep operating, and if he kept making mistakes all the time, he would get no results and we would have no show.
Also, remember that these characters taken hostage or killed were police officers who knew that when they took on this job, there was risk involved, and they could not deal with these terrorists without someone getting injured or killed.