They described what they are doing in their documentation, but the core ethical problem here is that the only users that would use their service are those incapable of understanding how UST/Terra worked, because anyone capable of understanding would just deposit funds directly and get higher APR for the same risk! Extremely predatory.
UST fooled many ...not very bright people who genuinely didn't realize it's a ponzi scheme - but obviously smart and technically proficient founders of Stablegains' have no such excuse. Zero room for doubt - they fully knew it's certain to collapse eventually, banking on their legal terms to protect them from liability while privately profiting as long as it works.
Founders of Stablegains belong in prison and everything they own should be confiscated and divided among victims. Sadly they are probably safe - as knowing the inevitability of collapse they must have felt their legalese to be ironclad.
Stablecoins are literally modernised promissory notes and the people hawking them are unregulated banks. It's incredible the people selling these stablecoins are not being regulated as if they are banks.
Of course they are not, but UST is. Stablecoins are different from each other. USDT, USDC and DAI are all collateralized (at least partially). UST is minted out of void by burning LUNA, creating demand for LUNA so creators get a profit and turn away, slashing all UST investors. It is an outright ponzi scheme hidden behind layers of DeFi jargons and borrowing trust from true stablecoins like USDC while being fundamentally different from any other responsible stablecoin.