I don’t think the DPRK wants to give an opportunity to basically any country in the world to plant spies. Considering the US used visits of the Atomic Energy Commission to infiltrate the DPRK in the 90s, welcoming thousands and thousands of difficult to vet corporate reps sounds like an open invitation for infiltration.
Y’know, Nixon was also ultimately responsible for the extensive bombing of Cambodia and the extension of the Vietnam war, both of which killed millions (the former by laying the ground work for the rise of the Khmer Rouge) BUT the important part was that he spied in Democrats! Not to defend Trump, he’s a vile removed that would serve the world best as fertiliser, but his legacy doesn’t even remotely hold a candle to the likes of Nixon, Dubya, Truman/Eisenhower etc.