He also claims that Google were about to do it, and then they stopped after his warnings. And presumably removed every trace of openai's responses.
A couple of things:
1. So, Bard could have been trained on ShareGPT but it's not - according to the same engineer who raised the concern (and google denial in the verge).
2. Since he directly joined OpenAI, he could have told them and they could have taken action, and nothing is public on that front yet. Probably nothing to see here.
Edit: The engineer too wasnt directly involved with the Bard team, it appeared to him that Bard team was heavily relying on ShareGPT.