this seems suspicious. generally you seek out foreign courts when you want to set a precedent or touchstone for a favourable outcome in your court, or you want to cherrypick a legislative tome thats favourable to your case. this strongly suggests that had Zuru just litigated this in New Zealand, they would have lost.
Or, more likely, they intend to lose but also expect to take advantage of America’s rather unique legal procedures with expansive discovery powers (you can discover nearly anything in America) and, probably more importantly, the losing party doesn’t normally have to pay for the winner’s fees. The latter part is what I would do when trying to send a message to employees not to speak out: "do this and we will make you hurt even if we have to go international"
That really hasn’t been the case since the Federal Rules of Civil Procedure were amended in 2015. The new rule requires that discovery be “neither unreasonable nor unduly burdensome or expensive, considering the needs of the case, prior discovery in the case, the amount in controversy, and the importance of the issues at stake in the action.” Fed. R. Civ. P. 26(g)(1)(B)(iii) (1983)