This is the odd case whose dicta may be more important than we now appreciate. It has long been Delaware law that a plainitff loses standing to pursue a derivative case when he is ceases to be a stockholder after a merger. The exception is when the merger is done solely to deprive the stockholders of standing to sue.
Here the Court seems to be saying that when a merger is the only way out for a corporation that has been devastated by wrongful conduct, the former stockholders may have a claim for damages even after they cease to be stockholders. If so, that is new law and this bears watching.