Well, if they have never released open source, they might not be the right developer for us. We don't have to chase after every type of person, we have specific needs.
Having said that, if I was hiring for a big corporation, I'd still get a lot of information from how they interact with the LLMs, and I wouldn't want them to 'game it' a couple weeks in advance so I'd look for older entries. I love how LLMs for the first time give me a real way to assess what people have been doing. And can even use them to vet crazy ideas people send to me.
Here is a real example that I did today, see what I mean:
https://chatgpt.com/share/68b878b8-8608-800a-8b6a-6bac1af36e...