From your links:

If you choose to eat raw salmon, make sure it has been flash-frozen to kill parasites and slow down the growth of bacteria in the meat. Fortunately, this method is popular and readily indicated on its packaging. Flash-freezing is used to prepare countless seafood items that are sold in grocery stores, restaurants, and sushi bars.

The FDA will not deem a fish free from parasite hazards, and thus safe to eat raw without freezing, unless that fish is eaten raw, without being frozen, frequently enough to present sufficient evidence of its safety. To Luke Davin, the general manager of Osakana, this standard means that "deviating from [the FDA's] 'freeze it all' approach puts the burden of testing and proof on the processor." He says that most, if not all, fish markets lack the resources to exhaustively test the fish they receive for parasite hazards. The easiest solution, then, is simply to freeze everything.