The author of that tweet clearly has an issue with the arxiv being an open repository where everyone can upload anything. There is nothing about open access in the tweet. And arxiv is not same as the concept or movement of open access. Most articles on Arxiv doesn't even have a proper license to fulfill the definition of Open Access in the BOAI declaration.
Further proof that the authors tweet is not about or against open access is that she publishes open access herself:
The context is that the author of the tweet hates fast paced open research (which IMO is a net good for humanity) and makes up the strawman `"can't keep up" + "anything older than 6 months is irrelevant" in CS` quotes to justify that position.
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.
I’ve hosted a few free services over the past 2 years. They are just utilities, nothing controversial, yet there are DDOS attacks ever few weeks from some Chinese IP ranges (especially Alibaba). Ended up just blocking the ASN as the JA3 fingerprints were spoofed and they were sending legitimate looking data (thus difficult to identify and block)