Yes, German women are justified in hardening their stance on immigration based on the Cologne sexual attacks. Hundreds of women in Cologne were attacked on New Year's Eve by a group of Arab and North African men were did not feel that they had to obey the laws of the country. Requirements for immigration should mandate a minimum amount of loyalty to Germany and its laws.
No one can presume to know what it is like to be a woman, unless they are a woman. As a male who has never experience rape firsthand I couldn't begin to imagine what it feels like (never mind know how a victim's thoughts on the matter are). Furthermore, if fact the attacks are proven to have taken place in a coordinated manner I see it as absolutely justified to harden one's views on immigration.
German women justified in hardening their stance on immigration. This is because the crimes actually happened. They were not even threats, they were not even just leering, but actual physical attacks. Angela Merkel is going to have a very hard time for years to come for her leniency and open door policy. She turned her back on her own female citizens.
German women are not justified in hardening their stance on immigration based on the Cologne sexual attacks. The actions of one person or a group of people should never influence how we treat others. This is the same logic that fuels our racist, sexist, hateful society. The only way to obliterate hateful acts like rape is to kill them with kindness. We need to teach people by example the benefits of education, love, kindness, and generosity.