"He tried to kill me, so he's dead." Michael did not try to give any explanation, just stating the facts.
Despite the misunderstanding having been cleared, Michael did not feel guilty of killing Gregory. That guy had the intention to kill him from the start, so, he deserved to die.
And considering the fact that Bob was involved in the death of his parents, Gregory taking action like that, it seemed that it might have been Bob's plan all along?
Back then, Michael had not really paid much attention to Bob's reaction when Gregory was attacking. So, he was not really sure if Bob's reaction was genuine or not.
Regardless of all of that, since it had already happened, then so be it. If he was again faced with such a situation, he would obviously not hesitate to kill him off.
Michael's response left both Newton and Matthew silent for quite a while. Even though they had kind of anticipated this, they still felt quite shocked when they really got the response.
