Yeah, it's hard to blame anything that happened on "insider knowledge" and even if we could, Bcash isn't a security as has been pointed out.
Regarding the "insider" stuff.... Coinbase's CEO said literally one week ago that they were planning to add "many more" coin listings. I've been speculating for a while that BCH would be added, followed by DASH and Ripple. They also announced months ago that Bcash would be supported by 2018:
Some traders also noticed that Bcash was added to the API a day or two earlier, much like how we've gotten the scoop on new Bitfinex listings in the past. The chart was also in a bullish accumulation pattern like several other alts. These news pumps happen to pretty much every altcoin out there. Nothing to see here.