Most experienced crypto users have adopted the habit of sending small test transactions before transferring large amounts of tokens, to first check that they're using the correct address. Oddly, this person did so in this case, but then went right ahead and transferred the remaining tokens to the erroneous address.
The person may have lucked out that they were using a centralized stablecoin like Tether, whose operators hold a substantial amount of control over freezing, destroying, and creating new Tethers — and could feasibly replace the burned tokens.