"what any user who happened to Google hiybbprqag randomly"
But it wasn't any user, it was a Google engineer and the circumstances were not ordinary. Those engineers were actively trying to get the results into Bing over the course of at least two weeks 12/17-12/31 according to searchenginland.com.
So Google, by doing this, has created up to a hundred or so bogus entries in the Bing database, to which I say, "big whoop". If Google had to pay damages for the extra infrastructure that Microsoft requires, the stamp to mail the check would be more than the check itself.
What I would classify as an attack is if, through a similar process, Google introduced bogus entries for real search terms, which they don't claim to have done.
IANAL, but if they have attacked Microsoft, that is probably a prudent legal strategy. Keep in mind that Google claims to have discovered this episode by noticing similarities between their results and Bing's which although it suggests and active program to monitor Bing, is hardly surprising.
On the other hand, however plausible it appears their claim about how they discovered it smells a bit of BS. It strains belief that Google never looked at the packets the Bing toolbar was sending home during browser compatibility testing. They lost their virginity a long time ago.
But it wasn't any user, it was a Google engineer and the circumstances were not ordinary. Those engineers were actively trying to get the results into Bing over the course of at least two weeks 12/17-12/31 according to searchenginland.com.