You're also neglecting another libertarian position: that individuals (and by extension, businesses) should be free to associate as they wish.
Don't want queers using your facility for activities ? Fine, don't rent to them. Where it gets sticky on DADT, is that government cannot be allowed to discriminate. But a set of rules that would prevent homosexual activism and favoritism could be put in place that would amount to DADT yet be immune from "discrimination" charges.
"The first person to describe himself as a libertarian was Joseph Déjacque, an early French anarchist communist. The word stems from the French word libertaire, and was used to evade the French ban on anarchist publications.[18] In the context of the European socialist movement, libertarian has conventionally been used to describe those who opposed state socialism, such as Mikhail Bakunin. In the United States, the movement most commonly called libertarianism follows a capitalist philosophy; the term libertarian socialism therefore strikes many Americans as a contradiction in terms. However, the association of socialism with libertarianism predates that of capitalism, and many anti-authoritarians still decry what they see as a mistaken association of capitalism with libertarianism in the United States."
Who told you that the military cannot discriminate? When in the entire history of America has the military not been able to discriminate against homosexuals?
As a liberal/libertarian, you are striving to discover for the first time in American history, a new right and then impose that new "right" on our nation, just like you guys did so much of during the 1960s and the Earl Warren court.