Complex sentence: The inclusion of UDT's as SEALs is a largely informal courtesy extended by the Naval Special Warefare community but that courtesy cannot confer the legal eligibility to wear the Naval Special Warefare insignia on a Naval uniform when it has not been legally earned.
Split into simpler sentences: The inclusion of UDTs as SEALs is a largely informal courtesy extended by the Naval Special Warefare community. That courtesy does not confer the legal eligibility to wear the Naval Special Warefare insignia on a Naval uniform until it has been legally earned.