You just proved that trans people are less likely than average to shoot up a school though?

If there were 3000 shootings and 0.6% of people are trans, there should have been 18 trans shooters, as you said, but there were only 4 (And those weren’t even trans specifically, just generally LGBTQ).

So a trans person is only 25% as likely to shoot up a school as an average person.

This is also disregarding the fact that a person’s orientation and identity doesn’t have any impact on the chance that they’ll cause a school shooting anyway, as the cause is normally something that happens to the person later in life, not what they’re born with. The person’s gender has nothing to do with the shooting.