First, I don't support suing the gun store, they were acting for the ATF in these sales. Any dealer would be in a tough position in a case like this because the agency trying to get you to help can also shut you down.
Second, is that they aren't suing the Border Patrol for violating their own use of force policy, sending some of the members of his BORTAC team into the field with less than lethal rounds. If you know somebody is armed you should never start with non lethal shotgun rounds. They sound like real rounds going off. What kind of response do you expect from bad guys in that situation?
The good thing about including Lone Wolf Trading Company is that Lone Wolf’s lawyer/s will use their forced participation as their primary defense. That will get more negative publicity for Holder and the ATF and open up a lot of ATF/DOJ files for discovery.
I suspect that they are including the gun store to insure that the ATF cant stone wall any information that the owners might have on this whole sorry affair. Given the circumstances, I doubt if they expect an actual judgment against the owners.