It seems a bit cynical to imply that people who care about mentoring juniors prefer to work in an office and selfish people prefer to work remote. Having mentored dozens of engineers, remotely and onsite, my evidence suggests neither approach is entirely superior for everyone, it depends on mentor and mentee.

It's just that, your preference - it doesn't have to be sinister or heroic, more or less effective. Some people prefer an office and some don't. That's valid enough on its own, isn't it?