Scanning for publicly-reachable proxy DNS servers is old-hat. I've been warning people about such since the turn of the century, and #tinydns is never going to be vulnerable in that way.
The more interesting attack, not least because Bernstein got it right all along, is the people that send queries with huge EDNS0 buffer sizes, asking for ANY against fsf.org (which is nearly 5KiB of response) and direct the responses at the tram port of some victim's router.