It's not clear who added the bytedance researcher to slack as a volunteer.

I would more question what they were doing in violation of the consortium rules inviting the employee, than that employee joining.

To be sure, there was a former Apple employee and a former Google employee held liable for data exfiltration. But ByteDance is the risk. Okay.

Edit: To all the downvoters, check facts vs. hysteria. You know, cuz science and facts and data and evidence and truth values.