I agree with Judge Hall and disagree with Judge Callahan on this one. Even though the latter's view not only garners the vote of Judge Robart (sitting by designation from the Western District of Washington), but is both moderate and plausible.
Simply because a single passenger makes an vague request for a "dander-free" area doesn't mean that a business can implement a policy that kicks all service animals for the blind out of their entire first-class area on the (utterly unsupported) ground that a dog would be a "direct threat" to the immediate health or safety of others. Much less, in my view, can such an issue be resolved in favor of the business on summary judgment.