According to, IslamQA Link, it is permissible for men to open a shop and sell women clothing. Now, let me teach you something simple.
I am very sure you probably buy things from Walmart or Gap or another other retail store that sells clothes. Now, women are the one selling the men clothes. The cashier may be a women, so what can we say here? Now if we were to turn this the other way around where men are allowed to be up front, then men are the only one left to sell this.
However according to IslamQA, a man can be a CEO lets say of the company, but leave the selling to the women. Or let's say the man has to do promotion stuff and it gets in the way of Islamic rulings on modesty, then it because non-permissible, otherwise as long as the intention is clear, everything is fine.
Apologize in advance: This post may sound a bit unorganized, well I am answering this not with complete thought in the early morning. But anyway, I hope this answer gives a good explanation may Allah guide you in the right path.