It certainly helps to have a vertical advantage. The hippo could only be able to reach the legs and head if they got close enough, so Siats could manage by chipping away. Probably something it did in hunts with chunky prey anyway.
@Harpy Eagle Enthusiast Also the main discoverer of Suchomimus officially said that the Specimen : was Not fully grown ! -- there could be more larger ones out there.
That's the reason why you occasionally see 12 / 12.5 Meter Suchomimus rendetions