wasnt Tista supposed to be bigger than lith?and here shes addressing him as "big brother"
"How?" Tista felt outraged at the thought that something that her beloved big brother had created for her might be used to abuse children. "This is a beautiful playground and some of my fondest memories are bound to the Magus Chair.
it could be that its because they are innocent (like the other said)
or it could merely be a front. him hiding behind a "innocent" mask to avoid suspicion