No, not really. Think about it: who is somehow trying to argue away school shootings based on arbitrary assertions? Do you think you can argue away the gun violence out of school grounds?
I would dare say that gun violence is bad all around, but here we are, trying to argue that some episodes should not count because of reasons. That would certainly reassure those attending those schools, as well as their family and communities.
Citation needed.
I assume your absolutist definition would only include incidents where a child made contact with and suffered harm from a fired bullet?
This data was compiled with the criteria it was to inflate the perceived number of "muh assault rifle" headliner-style school shootings. You're probably never going to turn on national news and see any reporting on any of these crime disputes that came to a head at/near a school. There is very little political willpower to do anything about these instances and not calling this shit out for what it is is a disservice to the people that are actually impacted by this strain of gun violence.
EDIT: after re-reading your comment a few more times, I think what you were trying to say is that it doesn't make sense that people would overlook some gun violence and worry more about other instances, but I've got bad news for you -- they do it all the fucking time. It's not that it's <people-they-don't-like>, it's <people-they-don't-think-about-at-all>, save when they make for a convenient data point.
It's simply not helpful to group them with the shootings that happen during school hours and target students/staff.