If you read the article, the author is talking about his relationship with coworkers, so I'm going to assume we are talking about one's relationship with coworkers. That being the case, I certainly hope you don't think any of your coworkers are "useless."
You don't have to be kind; you don't have to be anything. On the other hand, if you want to be a good engineer, with goodness defined as how much one contributes to the team/company, then you probably should be kind. If you feel like your teammate is unmotivated then it seems like if you want to be a good engineer you would do your best to motivate that person.
Having an uncaring attitude towards your coworkers could well lower their motivation which would mean your net contribution to the team is lessened as well.
You don't have to be kind; you don't have to be anything. On the other hand, if you want to be a good engineer, with goodness defined as how much one contributes to the team/company, then you probably should be kind. If you feel like your teammate is unmotivated then it seems like if you want to be a good engineer you would do your best to motivate that person.
Having an uncaring attitude towards your coworkers could well lower their motivation which would mean your net contribution to the team is lessened as well.