Barely beating not a good sign?

Not sure if I had heard of this before.  From a BBC article on body conditions  and how they may relate to personality:

Meanwhile, although a low-resting heartbeat is usually considered a sign of good physical health, when it comes to personality, the implications are darker. Several studies have found that a lower resting heart rate correlates with higher psychopathy scores. People who match this description show superficial charm, fearlessness and impulsivity. This is not too surprising considering studies already link low-resting heart rate with aggressive and criminal behaviour. The two main explanations are that low heart rate is a sign of fearlessness and that it can reflect an unpleasant state of being “under aroused”, prompting some psychopathic people to seek relief through violence and conflict. As ever, more research is needed to test these ideas.

I'm guessing that there might be a difference between those who have a very low heart rate through dedication to an exercise regime, and those who just have a low rate regardless of exercise.

For example, I thought Donald Trump's reported heart rate for his age (and with no exercise to speak of) was pretty low:  68bpm.   But apparently Obama and (especially) George W Bush had much lower heart rates:   56 and 43 respectively.    See this link for the comparisons between them.