The SoCast mobile app uses two types of functions to display content, one being the Activity Streams the other being 'In-App Browser' (for navigation items like Pages, Links or Promotions).
If your Home Navigation item is set to an 'In-App Browser' item (which currently it is Red Solo Cup Page), the URL in the Push Notification will automatically re-direct to an available Web Browser seeing as the 'In-App Browser' is reserved for the navigation item you have set.
It's for this reason we often recommend your Home Navigation item be set to an Activity Stream, to help maximize the functionality.