Not a fault of Go, the rewrite just burnt all the time they should have spent improving the product.
They had a working node server and decided to reimplement it from scratch. They started missing demos and weren't able to raise more from existing or new investors before they run out of money.
I suspect the CTO did it on purpose and was just CV building.
Often times the tech choice is not that important, you just need to get something out the door.