I'm surprised that Polo isn't offering to at least compensate in some way, though, given the fault is probably partially on them for offering margin trading on illiquid markets anyways...
...especially when their positions should have automatically closed in the first place.
I'm getting legal advice, and I've received confirmation that pooling losses is illegal.
The default is 100% due to Poloniex's negligence. If the other trading platforms didn't allow margin trading on CLAM, that's because they were smarter.