Interestingly enough, this is almost exactly how ISPs do it when they really want to get your attention. A couple years ago I forgot to update an expired credit card that I used to pay my spectrum cable bill. One morning every DNS request resolved to their "your account is about to be closed due to nonpayment" page. As I also use my own DNS sever I was surprised by this, and sure enough everything going out of my network on 53 was being grabbed up by their CGNAT and sent to their DNS server.