I don't really find this suspicious. It would probably be better for him legally if they found a way to raise the funds to keep FTX solvent. He has also already stated the SEC killed his attempts to save FTX. [1]
Why would a16z be involved? They didn't invest in FTX and turned them down for reasons likely related to their investment in Coinbase.
I agree that investors should be held more accountable. They throw out these millions to fraudsters and get to claim "oh, it was just a bad investment" and move on.