What's that got to do with guns?
Every bit as much as yours has to do with responsible gun owners.
No, your implication is that there is no such thing as a responsible gun owner, which is pure unadulterated horse manure. If we use your definition then there is no such thing as a responsible homosexual, or car driver, or chef, or whatever you decide you want to attack on any particular day. That's why your whole statement is a logic fail.
It is a cheap shot, taking advantage of a terrible accident to further your particular political goal. I can do the exact same thing whenever a gay person makes a mistake, or engages in unprotected sex etc. etc. etc.
It would be equally disgusting.