Because "Death to America" only applies if we're not talking about McDonald's, Froot Loops, and (this is my favorite) New York-style Bagel Chips.
ISIS fighters are apparently just like every other unbelievably annoying human being with access to the internet, so they can't resist sharing pictures of their food on social media. Most of it is pretty ho-hum stuff (hold this thought, though), but it becomes deliciously ironic when you get to the images of McDonald's and packaged junk food:
"Look, guys, all I'm saying is, America is the Great Satan and all, and we should of course kill them, but McDoubles are really fucking good, so how about we make an exception there? Would it help if we pretended McDonald's was, I don't know, Latvian or something?"
Those McDonald's burgers were apparently smuggled in from Turkey, which means they were pretty damn ripe when they got there. Not that it makes a huge difference (I'm pretty sure McDonald's food is non-biodegradable), but you know your food situation sucks when day-old pseudo-beef and processed cheese is a treat for you.
It's worth noting that the DailyMail post I've linked here is itself pretty dumb. Look, ISIS deserves all the criticism it gets and more, but if you're going to look at these pictures and your reaction is "how dare they lack a balanced diet!" and to critique their meat quality and photographic skills, you're missing the point more than a dartboard in a room full of blind people. Of course their food quality sucks; the nominal "country" where they live is a war-torn shithole presided over by a brutally repressive and (if these pictures are any indication) wildly hypocritical regime. Was that not obvious from the fact that in half of these images, the food is just sitting around on a super hygienic bed of dirt? Did that not fucking clue you in? But yes, DailyMail, I'm sure ISIS's great sin is "soggy-looking chips." How dare they.
Look, if you're going to criticize food pictures for looking bad, at least try to make it funny. That's your only job, and the person who wrote this isn't even trying. This reads like the author was so shocked at their lack of culinary sophistication that they popped their monocle and thought "I know just how to cut those ruffians to the quick: a comment about their catering's childish simplicity!"* I'm not saying your insufferable smarminess makes me want to side with ISIS or anything, but as writers, our best weapon to fight oppression and injustice is humor, not whatever the hell this is. I'm somewhat of an expert on being an asshole, so trust me when I say that if you're going to be an asshole, at least try to be an entertaining one.
* "Childish simplicity" is an actual quote.