When you use a trade name of someone else in a commercial property, it must be properly credited for fair use. The back of the box will have a copyright to ubisoft, all rights reserved. If they used another company's name, they are implying by the blanket copyright on their box that they own THAT name as well (since Grumman is not credited as owned by NG). NG has no choice but to sue, since failure to defend a name allows others to use it as well.

Ubi screwed the pooch on the PF box, big time. It left them open to whatever NG wanted to do to them. You'd think a company of their size would know that nothing should ever go to the printer without a lawyer looking at it first.