You don't understand how the Elder Gods work then
They don't really concern themselves with mortal affairs like lives lost and invasion at all, the only gods that really do are the lesser protector gods like Raiden
Smaller scaled problems like invasion by itself is why they even have protector gods to begin with, the Elder Gods leave them to handle those kind of responsibilities while they worry about larger things
The only thing they really care about and I'd say rightfully so is keeping the One Being at bay and the realms as a whole, more specifically the possibility of the merger of the realms
That isn't really being a dick, that's just their MO
Although I do agree that Shinnok's invasion is most likely going to make them think twice about things, but if the Elder Gods do get slaughtered, I would blame that less on the Elder Gods themsevles and more on Shinnok's cunning. He was one of them, after all, so he knows how they work