It is ok to use this new ABAP syntax about table expression here since object_ext is passed from UI framework and it is rarely possible that there would be partner or customer to manually pass any other value to parameter it_data.
According to ABAP help, if no row by specified key could be found, exception will be raised, instead of sy-subrc set to a non-zero value for READ TABLE XXX.
so ABAP provides another key word DEFAULT which allows you to provide a default value if specified row does not exist to avoid exception. In example below, line 17 will raise exception while line 19 not.
In Java 8 there is similar mechanism: new class Optional is introduced to avoid application developers’ endless of If XXX != null code to check null:
Unlike many other annotation, this Utility class is not implemented in JVM layer, but just in language layer, as a result it is very easy to develop an Optional class in ABAP as well.