"If you have physical access and enough time then yes anything manmade can be manunmade however this does not mean that you cannot design something to be truely secure if you can discount physical access."
I doubt it. As long as you can access it, locally or not, you can probably find a way to turn necessary functions into exploits and eventually into privilege escalations. I mean, we even have malware that can use Sneakernet and jump air gaps, for goodness sakes. Bet you pretty soon someone will come up with a way to remotely bombard something like a keyboard wire with a focused electromagnetic beam, allowing one to type a physical keyboard without ever being near it. It's kind of price of admission: what man can make, man can break.