This is pretty much the textbook definition of a patent troll - company acquires other company for patents, does not make a product, and then starts suing others for patent infringement.
So what? If company shouldn't be able to sue in such a scenario, then what is the value of the first company that wants to be acquired? What is the value of the inventions it came up with? Why would an investor invest in a future similar company if it knows the IP will be worthless should the venture fail and asserts need to be liquidated?
People hate on trolls all the time, but the fact is the U.S. economy would grind to a half if anti-troll rules such as "you have to use the patent in the market in order to have the right to enforce it" or "you have to be a successful and profitable company to enforce your patent rights" are made into law.
The real trolls are the small companies that sue for low-dollar cost-of-litigation damages and have no resources nor will to actually go all the way to court, and prey on small unsophisticated defendants. This here is not a troll: it's not going for low-dollar cost-of-litigation damages, it has the resources to go all the way, and it's targeting a very large and very sophisticated defendant.