An early, and IME impressively reliable, sign of whether a player will turn out to be a problem player or a good player is how they handle the churn and inevitable character turnover of low-level play.
Which direction did you find the link to be, though?
Because I have seen a link here too, but the link I've seen is that players who don't care if their character dies at all, in a modern D&D game (rather than an OSR like DCC), are usually problem players, because they:
A) Tend not to roleplay, and tend to metagame very heavily.
B) Don't play well with players who do RP, or don't metagame, even pulling faces or the like.
C) They are by far the most likely players to engage "outright dumb[expletive]ery", like murdering NPCs, stealing for no good reason, backstabbing the party (usually also for no reason, playing "Chaotic Stupid" and "Lawful Stupid" characters.
D) They're also weirdly a lot more likely to be pulling their phone out and messing around on it - even watching videos and trying to show them to others - I think because they're kind of stimulation-seeking or something.
E) Absolutely the most likely to argue pointless rules with me as the DM. Maybe not ones about whether they die or not, but definitely ones that nobody needs to argue about.
If I'd only seen one guy like this, I'd put it down to "that guy" but I've seen multiple.
Also, hard against any suggestion that players who care are a problem, I've played with two players who burst into tears when their character got killed (as adults!), and both of them are actually really good players in pretty much all levels - reliable, cooperative with the party, thoughtful, good RPers, don't
This is very specific though - it's not the case, for example with CoC. With CoC, what I've seen is far less of a link, basically none - I've seen players who would pretty much be in tears if their PC died in D&D or a similar game, who are absolutely fine, even think it's a little funny if it's CoC, because with CoC, that's part of what you signed up for. With modern D&D, it isn't. You say "inevitable churn and character turnover", but that's simply not "a thing" in 5E RAW/RAI. It's not a game where that's inevitable or even particularly likely. Nor does 5E offer any particular support for that play-mode. On the contrary in fact, I'd say 5E was a little too rules-heavy really work well for that. You want something with fewer choices and less conceptual investment. I'd actually say all versions of D&D from 2E onwards are bad vehicles for "low-level churn". There's just too much effort and specificity in designing a character.