Tony is the master of smoke and mirrors. As an excellent undercover operative (cannon), he would have no issues with presenting himself as a certain way. He only would have to keep up the 'show' upon meeting new people and then once and then throw something out a while to keep people on the right track.

For the most part, people make decisions based upon their first impression of you and keep you in the hole the peg you as. Coming off as a skirt-chasing manwhore just once seals their opinion and keeps them away from digging deeper unless something happens. It is easier for them to keep you that way because otherwise, they were wrong about you.

DNDT is not just for the military. We look at the things that we know as fact about him; military high school, high school jock, college jock, police officer, detective. As much as we tend to think differently, those professions or occupations are not something that people tend to think of for a gay man; they hold macho connotations and most people see a gay man as effeminate.