3-3-5: A player not wearing the pants/skirt properly and above the hips and/or a player not tucking in a team jersey (front and back) designed to be worn inside the pants/skirt, shall be directed to leave the game as in 3-3-4; a charged TO shall not alter this requirement.
I can see how the wording of this can mean if you ask someone to tuck in their shirt and they don't, then you direct them to leave the game. I can also read it the other way.
I am really ok with either one and with the suggestions already mentioned that if one or two reminders don't fix the problem then send them out. I do bet however that if you sent out the first person who did it in the game you wouldn't have any issues for the rest of that game and if all of the officials did it, you wouldn't have any issues ever. Except when the opposing team learns that if they untuck the star players shirt they will have to sit
If it was enforced early and often, the issue would disappear altogether. Go John Stockton!!!