BigPond disconnecting Trojan-infected customers

In my opinion this is not only a fair repsonse to a customers computer flooding the networks with bogus DNS requests, it is a necessary one. To their credit BigPond is notifying its customers of the problem first and the disconnect is temporary in nature. In other words, once they clean their machines of the offending viruses, and trojans, etc. they can get back online. In fact, I think all ISPs should do likewise. If garbage spewing forth from my machine is ruining the Internet for others, I want to be disconnected so that I do the least harm. Anyone's machine can be compromised and become a menace on the Internet. It is in the interest of the ISP, the compromised customer, and the Internet for the ISP to be a watchdog in cases like this.