So it's safe to say the 30% that left bitcoin did it's damage by clogging up the network
What damage was there? Bitcoin worked and is working as it is supposed to.
It seems to me that the only damage done was to the reputation of those who moved their hash rate to an alt coin. But that too is fine as they are free to do that.
They were able to congest the network and make the fees skyrocket. They then used this to propagate massive FUD and Bitcoin Cash propaganda, saying how Bitcoin Cash is faster and can handle more transactions.
But yeah, the hashrate is back on Bitcoin. I don't hold it against the miners, personally. They simply went to where it was more profitable, and it was more profitable to mine for BCH for a short while.