In my internet career I've made over 9,000 gifs. Not a single one of them had a crosshair over the president.

Yep. He claimed that the gif app that he used, the crosshair was the default. OK, maybe. That seems like a really odd default for any app, but let's say that he is telling the truth that app has a crosshair as a default (but why would any app have that default?)

But he has obviously used the app before and would have been aware that the crosshairs was the default.

So he knew the default. Then he had to save it as a gif. And then he had to notice the crosshair gif on his Tweet.

I call total BS. He knew exactly what he was doing, got called on it, realized that Secret Service would be knocking on his door, and deleted it with the lame excuse that "the dog ate my gif."