Sent TRX via off-chain transfer, recipient says he never got it — how do off-chain transfers actually get disputed/verified?

Made a withdrawal of 909 TRX to a TRC20 handle, off-chain transfer, exhibits "Completed," zero charge. [Screenshot attached]

Recipient's notice stated USDT-TRC20 solely, warned other belongings "could also be misplaced." I mistakenly sent TRX as an alternative of USDT. He's saying he acquired nothing.

Since it went off-chain, I'm assuming that handle is a Binance account — so shouldn't the TRX nonetheless be sitting there as an asset, just not the foreign money he needed? Or can a wrong-asset off-chain deposit truly go lacking/unrecoverable like their discover claims?

Curious if anybody's handled this actual state of affairs.