There is a risk if you have an extreme intake, but it's going to be pretty hard to do that by seasoning your food with lite salt unless you're doing something really extreme. Most people have a RDA of at least 2g of potassium, and I would hazard a guess that most people who are being told by their doctors to cut down on sodium intake probably aren't getting a ton of potassium from what they're eating.
Wikipedia quotes an LD50 of 2.6 g/kg in rats, so assuming (big assumption) that the figure is similar for humans, an average 80 kg human would need to consume 208 g of the stuff. Which is probably the whole container's worth.
I'm sure you'd die of other problems from eating that much salt before you die of KCl poisoning.
True, but doctors will still recommend it because of you tell people they can't have any seasoning they might just ignore you.
If you tell them they can have the other stuff, they'll find it much easier to comply and it's still much better.