Of course it is.  They're making a calculated economic decision.  They decided there are six books that make the brand look bad.  Six books that are poor sellers.  In order to protect the brand they made the calculated economic to allow those books to go out of print rather than risk damage to the brand.  

One of the things that people seem to be incapable of understanding is that the vast majority of books never get a second printing, much less multiple printings or staying in print for decades on end.  

I also find it hilarious that all the "free market" lovers are now having conniptions that the market has acted through copyright holders.  

By the way, Mulberry Street enters the Public Domain in 2033 barring another copyright extension.  So people can go back to actively ignoring and not reading it.  

Actually, virtue signalling manifests itself when someone does something for the sole purpose of being admired for their moral rectitude. It is a thing (enough so that it actually deserved its own phrase). It's not a recent invention, mind you, since even the Bible warns us about people who are very vocal about their piety.

Refraining from acting like an a###le, as you put it, obviously does not instantly equate virtue signalling. Refraining from acting like an a###le is being a decent citizen.

Is stopping from publishing certain books being a decent citizen? It depends on the book, it depends on the reason, and it depends on how it is done.

If the publishers of Dr. Seuss had decided to stop publishing those books (for whatever reason, including the fact that a character wears a coolie hat) and not advertised the fact, they wouldn't have been bragging about how virtuous they were. They would just have taken a decision based on whatever reason motivated them, and nobody would have reacted either way. (I don't think they'd have stopped acting like a###les either, because they hadn't been doing so in the first place, as books with such innocuous caricatures can at worst qualify as being "dated". Nobody was saying "What a bunch of a###les!" before they stopped publishing them.) 

By making their decision public, the publishers hoped to garner publicity. Now what kind of publicity does one gain by saying "I'm no longer selling this or that"? The kind that comes from stopping doing something that's somehow reprehensible. The kind that says "see how virtuous I am". I find it convincing when a company states that they'll stop using child labour to build their cell phones, or stop buying wood from endangered forests. In this case, not so much.

Companies are always trying to increase goodwill and brand reputation. It would be a wasted opportunity not to say "oh dang, we have this problematic stuff and we are pulling it." It also gives them the chance to control the narrative and get their version out before someone remembers these exist and makes a fuss. If they pull them after the fact, people will say they only did it to save their butts. This way they can try to look good while they do it.

Also, I didn't watch the announcements. Did the estate actually make a proactive statement, or did someone in the media just make a stink to whip people up into a frenzy and get some views or clicks?

All true, but she was still fired (or "not renewed") for her opinions rather than for her performance. That means that one's opinions, insofar as they are judged to be upsetting to enough customers, are ground for dismissal. That's precisely what cancel culture is: demanding that someone be fired until the employer folds, even if that person is competent and plays well with others. It's like the write-in campaigns meant to save TV shows, but in reverse.

If it is progress, it's not going in a direction I find encouraging!

That strikes me as a very accurate assessment.

Knowing not to go on a tirade about Nazis on social media when you're a very public employee of Disney of all places seems like a bare minimum intelligence check to work there. Plus, she was warned and given a second chance. Beyond that, I would be shocked if Disney didn't have some kind of morality clause or something they make people sign.

I mean shoot, if you worked gathering shopping carts in a grocery store and walked around blabbing about Nazis I bet they'd fire you for that, too. Not because they think you are one, but that's going to wig out customers, and the company won't want to be associated with that.