He will able to stake only 1000 USDT and 1000 BUSD which is much less amount . yes , he can stake safely his USDT on Binance and he can redeem his usdt any time instantly from Binance if he want. and binance will give him profit every day according his amount & Staking percentage . it is really a good feature .
I will also recommend Binance too, they have a good track record and investors' funds are SAFU unlike other staking platforms with no track record, risky and a high possibility of scamming investors.
Binance has different options to stake and earn, depending on the amount the person is willing to risk. Stablecoin staking will not yield more profit unlike none stablecoins staking but with the market situation where the majority of coins are down more than -50% it is better to stake stablecoins till the market recovers.