If we’re talking food safety, I don’t believe those sea lice are any danger to a consumer. Don’t they just invade the gills of the fish?
The lice from the farmed fish devastate the wild salmon populations, so ecologically they are awful.
That to me is a pretty clear reason to avoid farmed salmon.
But you’re right, of course, if we should consider the environment as well. I haven’t eaten fish in 8 years, personally, partly because so much of it is fished or farmed in an unsustainable way.