The bicycle analogy is interesting, it us more like getting someone on a time trial bike and checking if they can hit 25 mph. That counts for almost nothing when doing a downhill mountain bike course. Can you communicate to people clearly? Can you convey expectations? Can you write simple and easy to understand TESTS?? Leet code is part of a cottage industry for interview styles that faang employees for lack of anything better.
I did one faang interview and omg I bombed so badly. A week prior, I did another with the same company and they couldn't stop calling me asking me to stop interviewing and work for them. The hiring manager wrote a love letter of how much I'd enjoy it there. It's crao, half of the senior engineers at that company can't pass their own interviews, it's a broken system. You can't know if a dev us good until at least 3 months after hire, if not 6.
This reminds me of an old anecdote:
Beginner programmers pump out 100 lines of good code a week. Journeymen programmers do 1,000. Master programmers do -100.
It's the same sentiment as the famous Churchillian quip: “I am going to give a long speech today; I haven’t had time to prepare a short one.”
But I think you are doing your now not_future_colleagues a solid by giving up. If you are that square to think there is only one way to reach the "prestige, benefits and pay of Google" and that is by excelling at some Leetcoding pissing context: I see you not solve issues that are exciting to solve which is exactly what I like to see in programmers.
What you are saying would be kind of like someone saying "I knew an athlete who could do a mile in under 4 minutes, but one time he got on a bike, fell and then never cared to try biking again. Therefore, the ability to ride a bike has nothing to do with athleticism." Which is technically true, but misleading. It misses the key idea that the main factor is the person not taking the bike seriously as if he actually decided to take the time to learn how to ride a bike, it's virtually certain he would be better at it than 90% of people because the underlying traits that make one exceptional at running would also make one good at biking.
It also sounds this person had a good temperament and personality which worked in his favor. That wouldn't matter though if he didn't have the cognitive ability to never miss deadlines and correctly design out code in his head and on paper before writing it as you say.