> Most companies consider MITM an external compromise since the malicious actor is not on the machine itself or has no-longer access to the machine(s).
Securing HSM+Laptop is impossible compared to HSM. If laptop is secure, why even need HSM ?
> Even most 'dedicated' systems do NOT have a direct link to the input terminals most of the times since they are simple usb keypads. Some smartcard readers for PC have pin-pads but this is rarely the case and they are way more expensive than a keyboard and a regular reader.
If usbkeypad is not connected to a network and not attacked by evil maid, HSM+usbkeypad is still secure. But laptop is complex system, always connected to internet and has loosly regulated physical access.
> HSMs are not "MITM proof", the system at-large has to be.
Again if whole system is secure why need HSM ?
If user satisfy few conditions of using HSM, such as being rubberhose attack proof, the secrets MUST be secure irregardless of how insecure the larger system is.