Big Rock, I think those who stated their need for discretion made their point clear that "outting" themselves would ultimately pose a risk to their livelihood...not that swinging is innately immoral, just that the misguided perceptions of their peers, supervisors, managers and clients (people not in the lifestyle with them) could render irreparable damage to their careers.
Honesty is extremely important in the lifestyle...but you need to keep that concept in context. Honesty about my lifestyle with my boss, mother, client, or the Starbucks barrista is not only irrelevant, its ridiculous. Honesty must take place between the parties involved in the act of swinging, but it is unnecessary with anyone else. And calling people hypocrites because of this is a little shortsighted.
Additionally, no one ever defended the act of denying or lying about involvement in swinging when asked. They just implied not offering the information in general conversation with a vanilla audience; keeping discretion with people who don't really need to know.