I was reading the Wikipedia Cuban Missile Crisis article, and it does seem that intelligence helped avert catastrophe. There are multiple points where things could have gone wrong but didn't due to people being smart enough not to do something rash. I suggest that even greater intelligence might ensure that situations like this never develop or are resolved.

Here are some interesting parts:

That morning, a U-2 piloted by USAF Major Rudolf Anderson, departed its forward operating location at McCoy AFB, Florida, and at approximately 12:00 p.m. Eastern Standard Time, was shot down by an S-75 Dvina (NATO designation SA-2 Guideline) SAM launched from an emplacement in Cuba. The stress in negotiations between the USSR and the U.S. intensified, and only later was it learned that the decision to fire was made locally by an undetermined Soviet commander on his own authority.

If this guy had been smarter, maybe this mistake would never have been made.

We had to send a U-2 over to gain reconnaissance information on whether the Soviet missiles were becoming operational. We believed that if the U-2 was shot down that—the Cubans didn't have capabilities to shoot it down, the Soviets did—we believed if it was shot down, it would be shot down by a Soviet surface-to-air-missile unit, and that it would represent a decision by the Soviets to escalate the conflict. And therefore, before we sent the U-2 out, we agreed that if it was shot down we wouldn't meet, we'd simply attack. It was shot down on Friday [...]. Fortunately, we changed our mind, we thought "Well, it might have been an accident, we won't attack." Later we learned that Khrushchev had reasoned just as we did: we send over the U-2, if it was shot down, he reasoned we would believe it was an intentional escalation. And therefore, he issued orders to Pliyev, the Soviet commander in Cuba, to instruct all of his batteries not to shoot down the U-2.

Luckily, Kruschev and McNamara were smart enough not to escalate. Their intelligence protected against the risk caused by the stupid Soviet commander.

Arguably the most dangerous moment in the crisis was unrecognized until the Cuban Missile Crisis Havana conference in October 2002, attended by many of the veterans of the crisis, at which it was learned that on October 26, 1962 the USS Beale had tracked and dropped practice depth charges on the B-39, a Soviet Foxtrot-class submarine which was armed with a nuclear torpedo. Running out of air, the Soviet submarine was surrounded by American warships and desperately needed to surface. An argument broke out among three officers on the B-39, including submarine captain Valentin Savitsky, political officer Ivan Semonovich Maslennikov, and chief of staff of the submarine flotilla, Commander Vasiliy Arkhipov. An exhausted Savitsky became furious and ordered that the nuclear torpedo on board be made combat ready. Accounts differ about whether Commander Arkhipov convinced Savitsky not to make the attack, or whether Savitsky himself finally concluded that the only reasonable choice left open to him was to come to the surface.[29]

At the Cuban Missile Crisis Havana conference, Robert McNamara admitted that nuclear war had come much closer than people had thought. Thomas Blanton, director of the National Security Archive, said that "a guy called Vasili Arkhipov saved the world."

Basically, a stupid dude on the sub wanted to use the missile, but a smart dude stopped him.

Yes, existential risk ultimately came from the intelligent developers of nuclear weapons. Yet once the cat was out of the bag, existential risks came from people being stupid, and those risks were counteracted by people being smart. I would expect that more intelligence would be even more helpful in potential disaster situations like this.

The real risk seems to be from weapons developed by smart people falling into the hands of stupid people. Yet if even the stupidest people were smart enough not to play around with mutually assured destruction, then the world would be a safer place.

That's a good point, but it would be more relevant if this were a policy proposal rather than an epistemic probe.

It's not the giant cheesecake fallacy, but Vladimir Nesov is completely correct when he says:

Capability increases risk caused by some people, but it also increases the power of other people to mitigate the risks. Knowing about the increase in the capability of these factors doesn't help you in deciding which of them wins.

Anyone arguing that existential risks are elevated by increasing intelligence must also account for the mitigating factor against existential risk that intelligence also plays.

That statement shows a way in which the claim that increasing the number of intelligent people will increase rather than decrease risk might be supported.

Giant cheesecake is about the jump from capability to motive, usually in the presence of anthropomorphism or other reasons to assume the preference without thinking.

This sounds more like a generic problem of technophilia (phobia) - mostly just confirmation bias or standard filtering of arguments. It probably does need a name, though, like Appeal to Selected Possibilities or something like that.