Sorry I wasn't clear there. Because most of the short-depth is controlled by centralized exchanges, there's a risk you won't be able to actualize your short (withdraw, either in crypto or to a bank account), even if it's successful -- they could just block you from withdrawing and/or report you for fraud.
The point is you can't distinguish transactions that are from an "attacker" when the underlying signature scheme is broken. The Bitcoin P2P network has some metrics to disconnect from nodes that might be trying to DoS you, but if a transaction has enough fees, is spending unspent coins, and has a valid signature, it's valid.
This work is important, and I'm looking forward to forming an opinion on it. Maybe a future post! For those who are interested, this is what I'm aware of:
1) Short markets in Bitcoin don't have unlimited depth, and the centralized ones are KYC'd so there's some risk there
2) What if it doesn't tank the price? One thing people have suggested is just burning all the vulnerable coins[1]; it reduces supply so maybe the price will... go up? The point is there's uncertainty.