It makes sense to use different music. Many adds use a single song for the entire ad while showing clips from the entire movie. A fight scene may be edited heavily for inclusion in an add, to the point where the original soundtrack may not match up properly.
To use the most recent Star Wars as an example, they played the familiar theme song through large portions of some ads. I can reasonably expect that this song will not be playing through the entire movie. What this person alleges they did with Suicide Squad would be the equivalent of cutting scenes of Kylo Ren and his triple-ended light saber, despite using that image heavily in the promotional material.