
It is available on other, quite popular, stores. GOG and itch.io are household names in PC gaming.

Valve is pretty upfront about being a business first and foremost. Their customers are loyal because they consistently provide high value at reasonable prices, even though they are in a dominating position in the market. They’ve taken unpopular decisions in the past, but never any that seriously alienated a meaningful chunk of their customer base.

Based solely off the trailer I can see how a big American storefront would err on the side of caution here. There is very little to gain from carrying a game decidedly built with controversy in mind, but a lot to loose.
With the publicity around it and sales still possible through alternative stores maybe things will turn out alright for the developer in the end. “Banned” media is always in demand, after all.

All I really wanted was SQ42 back when I supported it on Kickstarter. With my 20 bucks there’s no regret, but it’s quite funny where things have gone since then.
I install the latest alpha once every year and am both amazed and disappointed.
I don’t expect SQ42 to be released before 2030 and I do expect it to be a buggy, unoptimized mess when it finally arrives.
I’ve been thoroughly entertained all those years, though.

This group is shooting for very easy targets and they celebrate like they’ve won hard battles. It’s self indulgent but ultimately unimportant, nothing of value was lost here. If they keep it up long enough and choose a target people are actually willing to fight for, things might turn out differently.

It’s a big gamble on the demand of customers. If it pays off, Nintendo will reap enormous profits. If it doesn’t, they can always walk back on it and will probably be celebrated for it. They can’t really loose here.
Needless to say, I won’t touch Nintendo products with a stick. It’s a ridiculously greedy and aggressive company.
I recently got Star Trek: Resurgence during a sale and was very pleasantly surprised. It was the closest thing to a new TNG episode I’ve seen in years.
It does have issues, but I could easily overlook them for the writing and characters. I found the whole 10h extremely satisfying.

I finally started playing Suzerayn and it’s the perfect game for the current tumultuous times.
https://store.steampowered.com/app/1207650/Suzerain/
It’s about leading a country while managing issues like immigration, nationalism and the grip of superpowers.
I can’t stress how incredibly fitting it is right now. It’s also pretty great and very well written. You do have to love reading, though, it’s all about politics after all.
That’s literally how it works. If you run a store selling/licensing media you get to decide what’s on the shelves and what isn’t.