What? Yes it does. Whether you do (3/(total population of trans people))/(2826/(total cis pop)) or 0.1%/(total population percentage of trans people) it’s the exact same calculation. It all cancels out.

Edit: if you know the percentage of mass shooters that are trans vs cis, you can extrapolate the per capita data using population percentages.

Second edit, for clarity: You can do this because you’re either cisgender or you’re trans. There aren’t other population groups to account for. For the purposes of the data, trans is an umbrella term that means “not cis.” If trans people committed 0.1% of mass shootings, and represent at most 1% of the population, then you can clearly see that trans people commit mass shootings at a rate of 0.1/1 or 10% that of cis people.

We know how roughly many trans people there are, and we know roughly how many cis people there are. We divide those two to get 1%. We do the same thing with the number of mass shooters, and we get 0.1%. These are in the same units, of trans/cis, and so when we divide them, we get the direct rate of 0.1 or 10%.