So, your argument is that people who, because of Thiel's donation, aren't as afraid of a Trump presidency as they should be, those people need to know that Graham and Altman have cut their ties with Thiel, rather than that they simply disagree with him, and that, by insufficiently ostracizing their friend and business partner, Graham and Altman are somehow sabotaging their stated goal of reducing Trump's support?
You also have to consider that Thiel himself very likely is not a racist (and obviously not a homophobe etc.). He likely does not see Trump as racist or sexist. He may be misguided and may hold some crazy and infeasible ideas, but Thiel doesn't seem evil to me. He's probably attracted to Trump's other features and rationalizes the rest of his behavior.
This is the problem with the needle Altman is trying to thread: he is leaving open the question of whether Trump is as bad as Altman himself says he is. I agree strongly with Altman --- as you can probably tell --- that Trump is exactly this bad. If Altman means what he says, he should do what he can to shut this question down.
People can believe what they want. But Altman and Graham have a stated objective to convince people not to support Donald Trump. I'm doing them no favors by hiding the fact of how their actions work against that goal.