That will happen with a Herbal Ley with the more dominant species gaining a foothold & pushing the weaker species out.
I suppose if he has all the relevant documentation invoices etcetera he will be fine. We've yet to be able to control what grows & what doesn't! 🙂
"make sure the sward has a minimum 10% cover of red clover"
"make sure the sward has an additional minimum 10% cover of other legumes, herbs and wildflowers (not counting white clover, creeping buttercup or injurious weeds)"