Given that there's such severe concern being expressed by Anthropic about Claude being distilled, and the idea that the harness is part of the the moat, it doesn't seem super surprising that the other side of that would try to also make it harder for them to tell how well they're doing and what their approach is.
Why don't the major players open source their harnesses then? As far as I'm aware, the only time the source code for the Claude harness became available, it was due to a mistake (which is it's own whole thing).
I'm not saying you're wrong necessarily, but I do think that when the actions and words of a company conflict, it's a pretty safe bet that the words are just posturing and the actions better reflect their actual belief. In this case, regardless of what they're saying about software being easily writable now, they clearly seem to at least think there's something valuable in the harness if they're not open sourcing it.