Not an ad hominem. An ad hominem argument attacks the character of the speaker independent of the argument and is a specific subset of non sequitur.
Whether an organisation is racist or not is highly relevant to whether we should trust their findings on matters of race, in the same way that someone being a salesman is relevant to whether we should trust their opinion on products they are selling.
If the accusation was that they were homophobic or sexist or a bunch of drunkards, that would be ad hominem. As it is, pointing out that they are racist is a very relevant and useful contribution. Although we cannot assess the objective validity of their findings based on that fact, our assessment of the probabilities change greatly.
Whether an organisation is racist or not is highly relevant to whether we should trust their findings on matters of race, in the same way that someone being a salesman is relevant to whether we should trust their opinion on products they are selling.
If the accusation was that they were homophobic or sexist or a bunch of drunkards, that would be ad hominem. As it is, pointing out that they are racist is a very relevant and useful contribution. Although we cannot assess the objective validity of their findings based on that fact, our assessment of the probabilities change greatly.