I'm just annoyed that people still see Valve as a game "developer", have they made any recent games barring their Hearthstone knock-off?
Because (I'm assuming) the US as whole is having issues with large tech companies who are very eager to shoot themselves in the foot - on top of all the COVID and domestic issues. There's been a ton of scrutiny put on Apple and Epic Games Store (which they put on themselves) about how much digital stores (like Steam) make per transaction - which is Valve's entire bread and butter. Facebook and Twitter keep sticking their dick into the 2020 Election, but any harsh lawsuits they find themselves embroiled in will also likely affect Steam (who also collects, compiles, and sells data). If Fortnite/Overwatch are branded as "predatory gambling aimed at children" that's also going to affect Steam's bottom line (as DOTA/CSGO/TF2 all have lootboxes). There's also the threat of absurd lawsuits over Copyright (example - Blizzard/Activison vs Valve over DOTA2) which they settled, but if they lost it could have been very damaging - and no one knows what the settlement was for.
Valve doesn't want to attract talent (more than they already do) - they have it. Gabe stated that all of the shenanigans have brought his team's productivity to 25% of what it was - he just wants his existing guys to operate at 100% (or more) capacity. I'd strongly suggest (again) that considering Valve's forays into VR/AR/experimental tech - they need a large lab space to collaborate in as a team and most developers can't nearly as much "from home" as a regular developer.
I'm sure there's other places than NZ that could accomplish all of that, but he might just genuinely like it there and is taking cues from other developers like CDPROJECTRED (Poland) or Warhorse Studios (Prague) in terms of how to setup a team outside of the USA.