The tweet says "arxiv is a cancer". It's obviously reasonable evidence that some people don't like arxiv. You are splitting hairs.
Further proof that the authors tweet is not about or against open access is that she publishes open access herself:
https://jlm.ipipan.waw.pl/index.php/JLM/article/view/292
The example was actually a Gatekeeper who values peer review before publication.
Additionally, Arxiv won't kick you off their platform if you post a preprint there, and then you get published in Nature.
In other words, the reason it does not change the point is that Arxiv does not weaken the publication process for the actual journals the preprint will be submitted to. You still need peer review to get published and you are still incentivised to do just that.
You could argue 'preprints ARE publishing' but I'd need to be convinced of that point because I don't agree for the reasons stated above.
There's timeless beauty in CS, but there's also a lot more fertile ground for research in CS, given how young the field is compared to the older sciences.
and I've offered at least as much evidence as you have.