Now that I've responded to your enlightening objection, if you feel like actually discussing the subject of "don't ask, don't tell" and helping me to understand why some people believe it is homophobic, that would be appreciated.
Sex is definitely one of the most prevalent topics in our daily lives.
Expression of sexual things is arguably in almost everything we do as human beings and fundamental to how groups of people interact.
Consequently, sexual identity is more than just a small facet of one's identity, it is a major element.
One's own esteem is not, nor should it ever be, considered an individual's responsibility, but is instead enmeshed in the social situation with which they are taking part. Social acceptance is a generally necessary element for satisfaction with life.
Thus, not being able to express one's identity openly leads to self-repression and thus a policy that asks someone to do such a thing is repressive.
Things that repress gay people, specifically, are generally labelled homophobic.
That is why I consider DADT homophobic. But, I tend not to use that word and would prefer the less ambiguous, "repressive" word.
If you can't understand how something is repressive without putting it into context, imagine not being able to wear your wedding ring, not being able to talk about your marriage, not being able to discuss your kids, not being able to express affection for that cute girl you admire in front of your soldier friends for fear of letting them know you're heterosexual, and then really begin to understand just how much of your social communication has your sexuality embedded in it, in some form or fashion, and then try, however impossible it is, to understand what life would be like if you had to neuter everything you say from having any relevance to that.