The following article contains spoilers from Nightwing #93, on sale now.
Despite Nightwing #92's massive cliffhanger, Heartless did not succeed in forming an alliance with Blockbuster. This is largely due to how assertive Heartless came across, but in the process, he insulted Blockbuster in a devastating way, while also exposing what truly motivates the notorious thug, something that's as petty and sad as Heartless makes it sound.
In Nightwing #93 (by Tom Taylor, Bruno Redondo, Wade von Grawbadger, Adriano Lucas, and Wes Abbott), when Blockbuster rejected Heartless' proposed alliance to try and kill Dick Grayson, the two almost come to blows. However, when Heartless had a perfect shot to rip out Blockbuster's heart, he refrained from doing so. His reason: There was no one who would mourn Blockbuster's death, thus making him not worth killing.
It was a vicious insult because it was ultimately the truth. While it revealed that Heartless intentionally selects victims with loved ones who will be hurt by the murders he commits, it also exposed how empty Blockbuster's life truly is. If he died then and there, no one would be upset about his death. Shocked maybe, but not sad. In fact, there's a strong possibility that several people would celebrate the news of his untimely demise. Nightwing certainly wouldn't lose any sleep over it.
This led Heartless to contemplate what would hurt Blockbuster. He has no loved ones, so that vulnerability is out of the question, but there has to be something he cared about. Something that gave him a reason to get out of bed in the morning. Something that, if he lost it, would wound him in a way no physical confrontation could.
Of course, Heartless reached the same conclusion that fans did: control of Bludhaven. Blockbuster has done everything in his power to ensure that the city remains firmly under his control. He has people within every branch of government, and he has been working night and day to try and derail the Alfred Pennyworth Foundation, a task that is easier said than done. Yet even that minor loss of control was enough to grab all of his attention and fury.
Hearing all of this out loud must have touched a nerve in Blockbuster. He certainly didn't react to what Heartless was saying in a rational way. After being called out for having no real reason to live beyond his petty need for control, Blockbuster opted to hurl a desk at Heartless, sending him crashing out the window of his skyscraper office. He may have won the physical altercation, but he lost the mental one. His reaction only confirmed Heartless' beliefs. In the absence of any true reason worthy of living, Blockbuster has taken the city as a means of filling that void. Without it, he is nothing, so taking it is the best way to hurt him.
Now that the moment has passed, it is clear why Blockbuster is going so far to maintain absolute control over the city. There is nothing else for him. If he loses the city what else does he have that he can say is valuable in his life? It explains why he's going so far to derail Dick Grayson's plans and adds a new level of danger to confronting him over the city's future. After all, there is nothing more dangerous than a person fighting for what they love.