The linked article by Elizabeth Bruenig in the Washington Post is an understandable attempt to make something good come from an intolerable situation. I agree the students she mentions are heroes, and we should never forget that a great number of our heroes are so young. But they were heroes in a cause they should never have been a part of. And that cause is precipitated by unvarnished, unabashed greed abetted by political cowardice. It is heroism in the midst of absurdity.
When I was a freshman in college I read Vonnegut’s Cat’s Cradle. It is a parable about human stupidity; the creation of a technology that could end the world named ice-nine. It was secretly preserved for no apparent reason, and unleashed by accident. The final scenes before the end of the world occur on an island where people who cannot be provided decent housing and a fair living were offered comfort through a religion based on happy lies. The last sentence portrays the founder of that religion declaring if he were a younger man he would write a history of human stupidity before lying on the ground to commit suicide by ice-nine while thumbing his nose at God.
The heroism of Howell and Castillo is of this kind. The hopeless gallantry of thumbing one’s nose at an ideology based on lies one is powerless to resist.
A martyr is someone who dies for a cause (μάρτυς: witness). The only cause these kids died for is the profits of gun manufacturers. They are less like martyrs and more like the scapegoat, the one who dies for the sins of the people. In the days of Israelites wandering in the desert in search of the Promised Land God instructed the priests through Moses to lay all of the sins of the people on a goat chosen by lot who would be driven out of the community carrying away the people’s guilt.  The children killed in our schools pay the penalty for our sin of stupidity and greed. They are not martyrs according to the traditional definition of the word: “a person who is killed because of their religious or other beliefs.” They are sacrifices, and the sacrifice of our children on the altar of a contorted misunderstanding of the Second Amendment is a holocaust, (Greek ὁλόκαυστος, “a sacrificial offering that is burned completely on an altar.”)
We love our children and, if they must die heroically, we want their deaths to have meaning. But the only meaning we can take from these heroic deaths is the shame of our own folly.
 “When he has finished purging the inner sanctuary, the tent of meeting and the altar, Aaron shall bring forward the live goat. Laying both hands on its head, he shall confess over it all the iniquities of the Israelites and their trespasses, including all their sins, and so put them on the goat’s head. He shall then have it led into the wilderness by an attendant.” Lev. 16:20-21, NABRE
You can determine the excesses of an era by its martyrs. Essential to the story of a martyr is that they did not wish to die but rather chose or accepted death over some unacceptable alternative. The alternative – the thing being selected against – contains the fervor of the age, and it signs its name in the blood of martyrs.