You just have to measure the risk you're willing to take. What is the *actual* odds of getting a tapeworm from said salmon? Find some statistics and see if it's a risk you're willing to take.
I'm a fan of raw meat in various forms. I get local beef and trust my butcher, so eating raw ground beef is a risk I'm willing to take. Occasionally I will eat raw venison or bacon (yes bacon) from my butcher. The risk isn't that big that I'm really concerned, and I figure if something does happen, that's what the doctor's for.
Shoot, even raw eggs- if you buy conventional grocery store eggs- is a 1 in 10,000 risk in getting salmonella from eating them raw. Pastured eggs is probably more like 1 in 30,000. I'll take that bet.