"Healthy" is not a weasel word, but one half of a common term that people use[0].
>If someone is paid to literally write code, it's perfectly healthy for them to want to only write code and not provide free labor in a different domain.
It doesn't sound like humbleMouse is getting paid to literally write code. It sounds like they're getting paid to write code and mentor junior developers. It's also not free labor. If someone works 8 hours, gets paid for 8 hours, and spent half of that time mentoring others (which is incredibly generous), then I don't see the issue.
In any case, if someone finds themselves in this position and are unhappy with it, they should talk to their manager or find a new job. There's no shortage for experienced developers.