If you want a new address type that makes sending funds from shielded very hard, it could be done without modifying the protocol by just defining a new encoding of a regular t-address.
Basically, a wallet could take the same t-addr as before but represent it as this new t-addr (let’s call it t2).
t and t2 can be converted back and forth as this is just a different encoding prefix: taddr ↔ t2addr
From Binance perspective, the code change is minimal. They need to add this conversion in their address generation.
Wallets that want to send to Binance also need to convert. At the same time, they must restrict the source of the funds to transparent. If a wallet doesn’t do that, these t2 addresses will look incorrect.
The only way to circumvent these t2 address is to convert from t2 to t manually without using a supported wallet, directly for binary, and then use the resulting taddr. I think that requires knowledge that 99.999% of the users don’t have. It cannot be done by accident.
All in all, it is just a few days of work. The encoding/decoding is already in librustzcash.
Thanks,
–h