Without reading the full article as TL:DR the idea seems a good one if you can manage the stocks of wrasse - Unless I missed a very important bit....
I always wondered why a natural solution to sea lice couldnt be found. If wrasse feed on sealice, then cultivate a thriving wrasse population - Less lice, less chemicals, less harm to fish, less harm to humans, cheaper healthier fish etc etc etc
Although I dont like the idea of farms in the first place - I just think a sustainable style of this method would be a massive improvement!
If I did miss an important bit ignore all the above