They said they were going to make a written statement, it's likely they'd already talked to someone about making that statement, which would still be retaliation.

From what I understand, CA labor law is pretty pro-labor about retaliation. When I worked in CA, there were mandatory labor law trainings every year or so, like 90% of which was "this is discrimination, this is harassment, this is retaliation, here are your rights about it"