0.03 BTC at todays exchange rate is about $120 USD. I think this is way too high for a low-risk altcoin exchange, even too high for a btc-fiat exchange.
It would seem more reasonable to set the security deposit at a fixed fiat amount, then convert this to btc, since the value of fiat is generally more stable than bitcoin.
i agree this is way too high right now, but it will be replaced by BSQ in the future.
As I understand, it will be an option to pay fees with BSQ but default will still be BTC.
The offer-maker can set the security deposit. 0.03 is the default value we have choosen when BTC price was 2500 USD. We will change in next release and maybe add a market price based adjustment assuming that BTC price will be 10k end of the year ;-).
No the security deposit is not planned to be pay-able with BSQ only the trade fee.