As noted by Matt Yglesias, that's basically an argument against having any laws at all: we don't need to do anything because someone who has decided to commit a crime will find a way to (insert illegal action here) anyway.
The photo included here is meant to highlight something politicians need to remember as they craft their non-responses and excuses for doing nothing at all: the generation subjected to this violence (while the so-called adults shrug their "well, there's nothing we can do" shoulders from the amen corner) will remember what you say, and they communicate with one another instantly across multiple social platforms. They will eventually be a force to be reckoned with at the ballot box, and they will remember the people and organizations who said "eh, a teenager would have gotten an AR-15 anyway if he wanted it."
How many kids have to be killed before a call to action is not considered a "knee-jerk reaction", as Paul Ryan called it? How many? If a certain amount of time must pass, what happens when the shootings become more frequent than the required non-knee-jerk waiting period?
By the way, have you heard about anyone getting killed by a machine gun lately? Do you know why you haven't?
