However, it seems to me that even Passport Core includes such code, as it has the ability to display SEED on its screen upon user request. I believe hardware wallets that offer the same functionality have also this part of code as well. What are your thoughts on this?
Each hardware wallet I own has that functionality. The seed and private keys are stored on the devices as they are needed to sign transactions, so I see no issues with displaying it on screen. What Cricktor is talking about (I think) is the exporting of the sensitive data and being able to send it around remotely for example. If anyone thought that couldn't be done because hardware wallet manufacturers always said that the keys will only remain on the devices, Ledger and their Ledger Recover extraction firmware is proof that it can with the right code.