They should say whatever they want, but remember that silence looks an awful lot like assent.
His silence here is assent. He'd rather we not recognize it as such, and I feel bad for him because I think he'd rather not recognize it as such either. But Graham's own writing spells out what makes his relationship with Thiel different than that of a relationship between employers and employees. If he can discriminate against mothers with young children, he cannot claim that the unfairness of discrimination prevents him from severing ties with Thiel.
The current chief of the Australian army has a great line on this.
"The standard you walk past is the standard you accept. that goes for all of us, but especially those, who by their rank, have a leadership role."