The moment Slack decided to apply a law to justify their action, it became responsible for understanding and correctly apply said law. Their beliefs are irrelev

The moment Slack decided to apply a law to justify their action, it became responsible for understanding and correctly apply said law. Their beliefs are irrelevant. If they misunderstood, they are still in violation of the law against discrimination. It is their action that counts here, not their beliefs. Would you say that robbing a bank is okay, if the robber believes that it's okay?