Why did the Guardidans of the Revolution not like "western" clothes and style?
The people in the council did not like that women got to dress the way they like and at the time they thought that rock music influenced younger audiences (similar to what is being said about video games nowadays). Also the people in the council were very religious and thought that the only clothes women can where are the veils and they have to cover the face or they were arrested.
Why did the airport security ban the posters from being taken within the country?
As I have stated before, the religious leaders thought that rock was "evil" or that it could negatively influence younger audiences. The leaders thought that rock could also somehow break the religion and give people something else to believe in, but we also can't forget that they hated the West and didn't want any of their culture inside the country. In the end, most of what they believed seems and is very stupid.