This guy should count himself lucky. The government now has assumed the power to execute by drone US citizens for "terrorist speech" and to kill their children later, and to kill anybody around them or their children when the missiles hit.

Why does he rate an investigation instead of a Hellfire missile?

World War One started without any participant having very clear ideas of goals. For a good part of the war, DEVELOPING war aims was a major controversy on both sides. They fought first, and made up goals as they went along.

Hitler did this in WWII. That was not only without precedent for world wars, it is how Hitler did almost everything. He made it up as he went, pushing where he saw opportunity. He even said that was a system, developed from German ideas of infiltration warfare. In a sense he was right, although it led to a dead end when short term opportunities led to dead ends in medium or long term.

Now did the British and French do it again in WWII? Maybe.

FDR had a longer term plan, to end the British and French Empires, the Japanese Empire, and prevent Case Black of German war against the US. He alone of the lot of them was clearly not making it up as he went along.

The Japanese by contrast attacked Pearl Harbor with no idea how they would end the war, other than outlasting American will to fight. In that, they were closer to the norm in both world wars.

An Israeli nuclear attack would run up against the truth pointed out above: this is not about an effective attack on Iran, it is about the ulterior motives to take the rest of Greater Israel, and those would be defeated by use of nuclear weapons.

A nuclear attack by Israel would change the world forever, in ways that Israel could not survive.
Ambiguity would be gone, and tolerance of their weapons would be gone. Netanyahu just said of the upcoming nuclear conference that the world knows Israel is safe, not a terrorist state whose weapons need be feared. Use of nuclear weapons would turn that upside down.

Furthermore, there would be many devoted to responding with a nuclear attack on Israel, and many ways for that to happen. Everyone accepts that Israel is too small to survive a couple of bombs. Sane Israelis would start to leave, to get out while the getting is good. Use of a bomb by Israel would be demographic suicide of the nation. Its people would leave.