The protest occured ENTIRELY on Syrian soil, because as far as the UN is concerned the Golan Heights is merely occupied by the IDF i.e. it isn't the sovereign territory of Israel. So as far and the UN is concerned the IDF didn't open fire to "protect Israeli sovereignty" but to "protect this belligerent occupation". And that's a completely different kettle of fish.
In three days, Greek coastguard rescues 2,500 migrants (Reuters)
from the article: Israel to complain to UN over Nakba Day conflagrations