The “big deal” is that this was an aid convoy being run by 2 NGOs that would have fed 78,000 people. The Red Crescent/Cross is a non-combatant international humanitarian organization, not an army.
The UN is also a non-combatant who had a clearly marked the area for humanitarian aid on radar, which is where the convoy was located. It’s more realistic that there was a friendly fire incident against the SAA than someone accidentally bombing a UN facility.
Director of Syria’s Red Crescent and everyone in the aid convoy has been suspected to have been killed. As a result, Assad also declared the end to the cease-fire.