Upside-down red triangle.
Why was it in the ad?
1) Someone knew what it meant, and snuck it in as a dog-whistle to the base
2) Someone knew what it meant, and snuck it in to ruffle up the feathers of the Outrage Community for a variety of reasons
3) Nobody knew what it meant, and it was in for graphic design purposes
4) Someone put it in as an emoji to represent something else, I don't know what, I don't keep up with emoji speak
5) Something else
6) Some combination of the above
Now, I just this moment tracked down the ad in question. The triangle isn't an emoji, it is a prominent part of the graphic design and messaging of the ad. Someone put the thing in there on purpose, to convey some sort of messages. In the context of the text in the ad, the message seems to be political.
So the choice of an inverted red triangle does seem tricky to explain. When I was at the National Holocaust Museum in DC recently, they had an exhibit of the clothing symbols sewn onto concentration camp victims, I believe the red one was for political prisoners and dissidents.
A bit of a coincidence perhaps...
trumpad.jpg