As I read the statement in the article, he didn't claim he was the chairman of Y Combinator at the time he was actually President. He claimed was the chairman at the time of the filing, 2021:
"Mr. Altman is an entrepreneurial and thought leader with a proven track record of growth investing within the technology industry. He is also the co-founder and CEO of OpenAI, a leading AI research and deployment company, and the chairman of Y Combinator"
And as mentioned, "president" and "chairman" aren't fuzzy questions for the law. Saying you're one when you are the other is a lying, not "fudging a bit". Lying in generally, say at cocktail party, isn't against the law. But lying to the SEC is definitely a thing that can have penalties.
And, yes, the article takes an appropriate "why would you even do that?" tone since it seems unlikely he'd get some financial or other payoff for such behavior. The main impression it gives me is of a pathological level of hubris/ego. Like a manager who j-walks in front of cop on company time.