Is there actually a reason to use kosher salt in this?

Yeah, take that, you. Actually, kosher salt is a fairly common ingredient and has been for some time, but salt has these days achieved the dubious distinction of being a fad food, and there is a great deal of what could easily be characterized as pretension involved in how it is used and discussed. To tell you the truth, I usually take salting instructions in recipes with a grain of salt; professional chefs generally use way too much for my tastes; recipes used to almost universally suggest salting "to taste", and for most cases that is probably the best bet. But for God's sake don't suggest that the Emperor is naked, the dude has no sense of humor.

There are various reasons people prefer one type of salt. Chefs seem to prefer larger flaked Kosher salt because it's easer to sprinkle by hand and gives more control over seasoning, some claim iodized salt tastes off, and some candy/pastry bakers say the anti-caking agents in table salt can cause things like fudges and caramels to crystalize. In this recipe it could just be because that's what this person is used to making food with, and that's how they made the recipe. If you have table salt, adjust the recipe to use table salt, what is there to get huffy about.

I imagine the reason the author calls for kosher salt is because of the small amount used, and the fact it is written with metric measurements. 3 grams of kosher salt amounts to much less if one is using finely grained table salt, and you could well end up with such a small amount that it would be difficult to weigh and manipulate. I suppose they could have used the inaccurate term "pinch"- but again, they want you to end up with a similar product to what they produce. You could as easily opt to use salted butter if you felt so strongly about the subject. However there was no need for the only slightly veiled jab at a person who posted a recipe to share in kindness. You are entitled to your opinion of course, but you do not have to express it in such an unkind manner. That in itself is an affectation as well.

Hey, you can't say stuff like that here. Everyone knows that salt is the most important food group, that's why we're willing to pay $10 an ounce for the very finest.