Having lived through a few "socialised losses" over the years, I remain somewhat sceptical. That initial ~10% could represent the easiest funds to recover from overdrawn accounts, or perhaps a portion of Poloniex's reserves/operating funds.
At least they seem to be repaying in BTC - like for like - rather than some internal token which has its value fixed to the exchange rate on the day of the event.
With Poloniex?
I think I've had some money in my lending wallet at Poloniex continuously since mid 2016. I had never experienced any "socialized loss". Do you think I was lucky? Anyway, I'm still missing 90% of the 16% Poloniex seized from my account, and that's substantial money. So I'm not so lucky...