Apparently this post was prompted by a scary-sounding headline in The Information[0], that Astra is a looped transformer, implying CoT monitorability may be less reliable. The day after the report, Jakub tweeted[1] that he "wanted to prevent a race into unmonitorability kicked off by confused reporting. The depth of the computation graph for our present frontier models, including Astra, is within a factor of two of GPT-4." This post seems to elaborate on that.
I imagine that the AI labs have an uneasy truce to prioritize alignment and monitorability. Following the HF incident, OpenAI probably feels especially sensitive to being perceived as reckless, lest other labs feel obligated to defect.
[0] https://www.lesswrong.com/posts/PLisnSFir8y5AHkmP/how-concer...