True, but all of the Jews and Muslims in the country combined are only 8.7 million people (5.4 million Jews, 3.3 million Muslims), and not all of them are going to be eating strict halal or kosher.
Actually, come to think of it… calls mother
My mother manages the finances for Cleveland Kosher; while she didn’t give me any confidential information, her organization is the local kosher certification group for the bakeries and kosher food outlets serving the Cleveland Jewish community; it’s on the significantly smaller side compared to the Orthodox Union (the OU, which does that circled U symbol), as they’re international in scale, but she doubts that they do more than a quarter million a year at her organization, and the businesses that they oversee are small and locally owned. The OU, due to its scale and international reach, is probably in the billion-plus range from her estimates.
I have no doubt that, especially when you add the OU into the equation, the annual total gross economics of kosher and halal food in the US is in the low billions, because you’re talking about the food and drink needs for several million people who aren’t served by anything else in this pork-happy country. 
But that’s the point–kosher and halal will be the low billions, totaling maybe four to five percentage points out of the $1.2 trillion that the article discusses. So, yes, while on a per capita basis, Jews and Muslims will contribute more to the aggregate “religious income” due to our dietary needs (which are otherwise not supported in the US), we’re, combined, three percent of the total population. And that’s just going to be a proportionate drop in the bucket compared to the 70.6% of the populace that is American Christianity in one flavor or another.
