I suspect some scammer was running a game on you. They tend to go "over the top," as "dumbass filters." If someone responds credulously to an outrageous claim, then they are a "good mark." The fact they ghosted you, tells me it was a scam. I have encountered many, many scammers, since leaving my last job. It's a pretty tough field, these days.
One of the reasons that I stopped looking for work, was because a lot of hiring managers and recruiters believe that it's important to insult applicants, right out of the starting gate. I think that HR policy, in general, these days, is to always keep the applicant in a supplicant position, so you are in control of the relationship. I think that LeetCode tests are part of that game. Sort of like "hazing."
What would be the purpose of this “scam”?
It may be as basic as getting you to open an infected document, of some kind. We tend to exchange a lot of stuff, when we do employment negotiations. I'd think an engineering manager, at a sensitive level, would be a juicy target. I've had any number of LinkedIn attempts to get at me, through offers of employment, basic networking, and attempts to get me to employ (I have a title as a CEO of a couple of 1-person companies, so I get a lot of these types of attempts).
My favorite ones, are the "attractive young women" that want to "link up" with me. I'll bet a lot of folks fall for that.
So you can know if it's really their portfolio.
Just asking some basic questions about the code in the portfolio will make it clear pretty quickly if it's their work or not.
Instead of wasting time with somebody floundering tests and offering excuses, or even have a cringe situation. That is why i also like the portfolio candidate.