That is my belief as well. Not so much that I don't think it is a good idea to do this. But I bet you a dollar Trump-Hater Extraordinaire LeBron James probably personally went to the Commissionner and demanded they shut down the season, knowing all the other leagues would follow suit.
The REAL smoking gun is that the NBA announced this decision within MINUTES of Trump signing-off from the Oval Office. Knocked what he had to say COMPLETELY out of the headlines.
Mission Accomplished.