Not really. Districts only really are vigilant about his behavior if they think the kid is demographically out of touch with the school, or a real problem-causer. Hiring PI's or proving residency is costly and time-consuming. When I taught, I had two of my students who lived out of district (I went to one of their homes), but my Parish didn't start the process because they were "good" students, and their test scores could improve our ratings. If this woman was black, and tried to get her kid into a rich white school, (which is what happened in Ohio), then the administration is more likely to flip out. Chances are, almost everybody has at least one student attending their old school who lived out of district on the DL.
I'm more concerned about this 15K number, which seems absolutely crazy. Surely the state of CT has some sort of matching fund program for per/pupil spending, so the local district wouldn't be on the hook for every kid. Even if they were, 15K for an upscale elementary school is way too much to be spending on one child, even for the entire year. Somebody is getting screwed here.