Sorry, I just dont quite get it. If he is lying, then he should be called on it. I know nothing about Hattrick except they are notable breeders in the world of Silkies,which I dont like and couldn't tell a good one from a great one anway. If he really has males from Hattrick, then yeah, that would be the bird I'd put in the ad, not a hen from "other lines", but I see people using dumb advertising techniques all the time.
If someone said their Delawares came from "speckledhen's lines", I would correct them since I was the fortunate recipient of someone else's hard work and that someone was the recipient of another long time breeder's hard work, then took them from that point on. However, I see nothing wrong with saying where the male and female lines began, truthfully. Well, I dont consider myself a breeder anyway, so maybe I just am not understanding the issue as well as I should. If he said they were Hattrick Silkies, then did not say that his hens were not, that would be completely wrong.