Pushing the boundary back is exactly the point.
In an ironic twist, there is truth in this... and liberals use this strategy to perfection. I personally cannot bring myself to encourage the protests that includes folks open carrying "assault rifles", but I won't condemn them either. Hell, it make me a little uncomfortable. But that is apparently the point. And I have to admit, it is working. Here is how...
It changes the sensitivities of people and affects social opinion. At one time our culture found the killing of babies (abortion) abhorent. Sucking the brains out of an unborn baby was a repugnant thought. Then the debate shifted to actually giving birth to a live baby and cutting it's spinal cord outside the womb (Late term abortion). To some extent, we have been desensitized to the original horror. There are many other examples; immigration, healthcare, taxes, gay rights, marriage.... I could expand on how we have been fooled into arguing details instead of premise based on liberal talking points and agendas.
In this case, folks are starting to be uncomfortable around folks with AR-15 strapped to their back at Star Bucks. They are far more comfortable with a clean cut citizen at Star Bucks open carrying a .45 on their belt.