The statement is probably true, but the only quote in the article that mentions “slop” doesn’t really support the headline’s claim:

”We need to get beyond the arguments of slop vs sophistication,” Nadella laments, emphasizing hopes that society will become more accepting of AI, or what Nadella describes as "cognitive amplifier tools." ”...and develop a new equilibrium in terms of our “theory of the mind” that accounts for humans being equipped with these new cognitive amplifier tools as we relate to each other.”

The article makes a lot of solid points about the AI hype bubble that Nadella is promoting in his year-end LinkedIn post, but it doesn’t seem like he was actually calling for people to stop using the term “slop.”