I don't even know who Sean Rooks is, so nothing I say is directed at him personally. But here's a couple of general observation:
A lot of players in basketball, (and NFL, ect) are not necessarily superbly fit. They are often big, strong, and heavily muscled, and yes they know how to push themselves up and down the court, but they're not marathon runners.
Have you SEEN the shit Americans eat? A professional athlete burns a tonne of energy, so they can eat crap and still keep to their playing weight. Problem is that their cholesterol is through the roof, which is a huge contributing factor to heart problems.
These guys make a lot of money, and many like to party hard. No slur intended on Mr Rooks, or any other player, but certain recreational drugs are notoriously bad for your heart.
Even athletes that have strictly avoided steroids whilst competing, when they get older and start to lose tone, may look for assistance retaining their muscles. Unfortunately roids are your hearts enemy.
Many of these guys would have huge egos to match their performances. Subconsciously they possibly feel quite invincible, don't like to face up to slowing down with age, and so continue to push themselves too hard and fail to heed the warning signs.
Whilst regular sustained cardio can certainly improve your heart, it doesn't get any bigger.
The biggest problem with obesity is that all that extra fat requires blood, and your heart has to pump that extra. But guess what, building massive muscles also requires more blood pumping.
Contrary to popular misconception, strenuous exercise is not always good for you. People often suffer heart attacks during exercise because they push themselves too hard.
The rule of thumb to determine your MAXIMUM heart rate is to take your age from 220. However a SAFE exercise rate is generally considered to be around 50~70% of your maximum. So the guys screaming and pumping massive amounts of iron, may actually be putting themselves at risk.