If your guest is a friend or someone you can speak frankly with you should explain that salt is not the risk to blood pressure that most people think it is. This is a common misunderstanding.
The real problem is an imbalance of sodium, magnesium and potassium that is caused by eating an unbalanced diet. Processed foods for example, have too much salt and not enough of the other two minerals. People who shake salt over everything also get an imbalance.
The answer is not to eliminate salt but to change your diet to eat natural, whole foods that have the proper balance of nutrients. A modest magnesium supplement may also help.
What's more, many salt substitutes are artificial, processed, commercial products that can do more harm than good. Fake food is never better than the original.
Salt is a tasty and healthy condiment when used sensibly in a healthy diet. There is no reason to become a salt tea-totaller and to impose your unnecessary and unreasonable habits on your host!
See #3 of the article of the link I've included and good luck in educating your guest! Lower Blood Pressure At Any Cost?