Your scenario involves someone sending coins to themselves, how am I trolling? Why would I send .2 to myself in order to create .3 change?
Here are some possible scenarios:
- I want to test Wasabi Wallet, and I'm required to send a small amount which can come back to my main wallet software.
- I want to mix less than 0.5 BTC, and I only possess an 0.5 BTC UTXO.
- I may don't like Wasabi Wallet as wallet software, and I only want to use it to coinjoin, which means I have to occasionally move coins from Wasabi to my main wallet software.
It's quite possible, and it is the user's fault. What the user does outside the wallet software isn't the wallet software's fault.
Yep, if your "main wallet" doesn't support WabiSabi coinjoins, then you should switch your main wallet to one that does: Wasabi, BTCPay Server, or Trezor.