The idea of expanding the use of period_type_concept_id is interesting!
However, it may simply shift the problem from the proposed column to the of problem of checking the correct type in OBSERVATION_PERIOD.
For example, people create a one day observation period just to cover the date of death of the patient. (data from some death source that per data quality check are now outside official observation period). To me, this seems like “cheating” and “covering up a data quality problem”.