Lomapaseo didn't dispute the effects of inlet drag.
The formula for net thrust is gross thrust minus inlet drag. Pure and simple; take away the thrust, and you're left with drag.
While reversing the airflow accounts for some retarding force, it's not much at all.
Many reversers don't divert the airflow forward at all, and it's not the diverted airflow that's accounting for the retarding force; it's the inlet drag.
Take away the thrust, all you have left is the drag. Very simple.