was the amount you have 0.0042650 or 0.00042650? Any input less than about 0.00045000 or 0.00050000 BTC is pretty much dust these days... as a standard transaction with the recommended fees of 240 sats/byte will need at least 0.00046000 in fees!
Well presuming his amount is correct, then that would amount to about $50 at todays price. <$10,500> so there should be more than enough to cover the miners fees. The fees on my Electrum wallet is usually very low in comparison to other wallets, so it should not be the case with this.
The fact that the error point to "dust" might mean that the miners fees are set at the maximum rate. I cannot remember if these fees are set dynamically or manually, but you might try to reduce the miners fee, to see if it would sweep the Private key.
Miners care about the fee per byte (or kilobyte). This is the total fee divided by the number of bytes in a transaction, such as 40 satoshis/byte or 0.0004 bitcoins/kilobyte. Use this https://bitcoinfees.info/
Remember, once the Private key is exposed to the Internet, we regard it as being compromised.