Considering that one of the main purposes, if not the main purpose, that Tzahal has women is for disgusting non-Tsnius reasons, I would consider it a terrible thing.
A girl wearing a Tzahal shirt is like saying (whether she realizes it or not) that she approves of the way Tzahal uses and abuses women. Wearing that shirt is like saying “I’m with them.” Would you consider it tsnius if a girl wore a shirt with a big picture of a rapper whose lyrics are misogynist and degrading to women?
A friend of mine – former chayal – told me how Tzahal bussed in chayalot to the soldiers for the express intent of hooking up. To me, this is institutionalized zenus and a just a notch higher than human trafficking. Bilaam must be laughing in his grave.