I'm not sure what the concern is here. In reality, the only way I see WA invoking that clause is in issue of where know abuse is happening - such as the ISP that was handing out copies to everyone.
Personally, I have nothing to hide so the clause doesn't really bother me at all. Regardless, in most states now, it is legal for software auditors to come in and check computers for authentic software anyway. I have seen several cases where larger companies have been cracked down on for illegal distributions of software such as MSFT Office and the like.
I really think they have to put that clause in there if they were to have any way of stopping an abuser such as the above mentioned case of the ISP.