Neither have I, but it’s very much a newbie move. Very often people attending their first meeting are curious about other people’s scores. And in the case of Spain (most of Europe in fact), 99.99999% of members have taken whatever standard IQ test is offered by Mensa itself; a lot of the stuff accepted in the US doesn’t have a local equivalent.
I have some quotes you can use:
“Does this have something to do with work?”
“I’m sorry, I’m here to work, not chat.”
“If you continue interrupting my work, I will have to report you to my manager.”
Remember, you don’t have to work “with” him, you have to work “near” him.
I’m generally the person that people feel comfortable with bitching about everything in their life/work/whatever. Until once I was in a conversation with our accountant when this type of annoying coworker interrupted with some stupidty which I can’t remember. The accountant said “You seem to be under the impression that I’m your friend and that I care. Let me assure you that I don’t care about you or your problems.” The guy laughed and left. It’s been my go-to phrase ever since.
“You’ll never convince me I’m wrong either, so I think we should just stick to work-related conversations from now on.”
If he continues to attempt to engage in conversation not related to work, it’s important that you reliably shut those conversations down. Eventually he may get the message. But even if he never gets it, you will have at least shut each conversation down instead of having to argue with an idiot for prolonged periods.
I’ll repeat…
You could always put your finger to your lips in a shushing motion, and point to your computer monitor, your phone, or the ceiling and give him a knowing look.
That’s why I don’t bother. I’ve been taking similar junk since I was six and know the ins and outs of a multiple choice test.
Tell him you’d love to talk to him about Amway. If he’s half as smart as he claims to be, he’ll hit the road.
Engineering prof: Every year we get a Physics major taking one of our classes who thinks it’s easy to design a stable living structure or sewer system.
Physics Professor: And every year we get an Engineering student taking one of our classes who knows for certain that Einstein was wrong.
Jees! The Stanford-Binet may only go up to 170, but when I took it I finished early, so I went back and answered every question a second time. Ended up with an IQ of 340! Honest.
How about this?
It can be a mistake to try to justify yourself to someone who wants to force you to engage. With someone like this I’d be tempted to say, “I’m not talking with you about this,” and refuse to provide any explanation. You don’t owe it to the guy to explain why you don’t want to discuss his crackpot ideas. He may think it’s rude, but that’s his problem.
There is an article in The Atlantic by some people who might want to study him. Perhaps there is an Ig-Nobel Award in the making here and you might share the glory.
Apart from that I can only recommend patience. Ignore him as much as possible. And at least he got one thing right. Nikola Tesla was a genius.
We had a guy like that at work. He was certain the moon landings were faked, among other things. You couldn’t teach him a thing.
But that worked out okay. He decided he didn’t want to work at our company any more after pissing a few people off, and heard that we gave generous severance packages. So he just stopped working, and waited for them to give him his big severance so he could go elsewhere. We warned him it didn’t work that way, but like I said, he was incapable of learning.
They fired him for cause, and he got nothing. Probably had a hell of a time finding another engineering job, too.
I’ve always thought it would be fun to find a situation in which to use Captain Haverill’s two-line put-down from NYPD Blue.
“If you can’t change your mind, it’s because you don’t have one.” – me
“You know, Scientology can help you with that. Have you heard the Good News about L. Ron Hubbard?”
“The crystal hanging around my neck says it’s time for you to leave now.”
As for Tesla: all his patents are in the public domain and available online. If his wireless power transmission stuff is so good, why didn’t the Soviets simply steal the patents and use them in the 1920s when they were trying to electrify the largest country in the world? Somehow, I don’t think it was out of Stalin’s well known love of the rule of law and respect for the capitalist system and its patent laws.
Tesla’s earlier work was brilliant but by 1910-1915 he was out of it,
Your new neighbor is insane and there’s pretty much nothing you can do about it.
I’m sorry, but that’s all I have. 
You are my new internet hero. Happy to buy the t-shirt if you want to put one on Cafe Press or Zazzle or one of those site.
My younger brother can be the worst person to talk to. I used to try to be polite, but discovered it doesn’t work.
“I can’t talk now.”
Repeat as needed. Never change the words, never smile.
“I don’t maintain diplomatic relations with Bullshitania, so I don’t recognize you as ambassador.”