They will have no proof who put them in there so there won't be a thing they can do!
I agree with your feelings that the government has way too much of their nose in things. I was looking at all the permits involved to get tilapia in VA. I mean really, the things die when the water gets too cold, it isn't like a grass carp or snakehead that can survive winters in VA.
The wording that allows government agents onto your property at any time to inspect is probably just like davasta said, a CYA type thing, they got better things to do than just wonder on to people's properties. I am a government agent as a profession and I know I got way better things to do than just aimlessly wonder around people's property even though the Supreme Court says I can in their open field's doctrine ruling. I don't agree with that ruling, but it is what it is...
I would be more worried about the fact that they could require you to pay for a sample to be taken to prove triploidy. That could be pricey! I think all this government tape is because in Louisiana you can sell both diploid and triploid grass carp, big brother just wants to make sure diploids aren't getting loose making a mess of the place.
