Alternatives to an INSERT Trigger
If T2 is derived data based on the contents of T1, then you may want to replace T2 with a materialized view.  If T2 is rarely accessed, and quick to derive, then you may just want to use a view.

On the application side, if you stop maintaining table T2, then the values it gets will become increasing incorrect.  This can be partially corrected by recalculating the derived values and updating T2 with the new values.