I agree with your first 2 sentences 100%, but not the last (not that there aren't double-standards apparent in many situations - just disagreeing on this one.)
And if this was a public forum, if they did not have their lives in his hands . . . and the big difference, if he were not acting in his capacity as an employee, I would feel differently. But he's covered not just by the 1st ammendment, but my American Airlines policy, and "American's 11,000 pilots are covered by "policies that affect all our employees" regarding the discussion of "topics that are inappropriate in the workplace with other employees and with our customers," an American Airlines spokesman said.