When you say keyboard, you mean wired or wireless or both? So basically if someone know you have crypto in your computer and had access to your keyboard, they can basically put something there and when its connected to your laptop, you are screwed?
I think they are talking about keyloggers, access to your copy and paste clipboard, etc.
If the attacker had physical access to your computer or keyboard or hardware wallet this is certainly a problem, and I would consider those devices permanently compromised (unless if you are dealing with small amounts of btc). Most of successful hardware attacks had physical access to the device.
There are also some attacks which you copy the correct address and paste the attackers address (when making transactions). This is why ledger nano confirms the address in the device's led. Maybe he was talking about that as well.
