Other than the obvious issue you mention with the exposed connection pins, it would seem to me that it would work...

You have essentially isolated the house from the mains when you open up the master breaker, all the rest is basically wire, which shouldn't (doesn't) care what the source of the current is.

Now as I am typing this I am trying to envision potential problems... the first I can think of is the lack of protection for the circuits in the wall where you plug in to provide the current... from that wall outlet up to the breaker box, those wires in the wall are not protected from any sort of overload... that is bad. The potential for fire if things draw too much current than the wires can handle is huge at that point.

From the circuit box back out to any other outlet in the house, you should be as protected as normal with the existing circuit breakers/fuses.

So to make it safer, you should have some form of inline protection from the generator to the "input outlet." (I know generators typically have their own circuit protection... but is it rated for the same current as the wires in the wall?) 15 A circuits are pretty common in modern homes... less so in older homes. 20 A circuits tend to be somewhat limited... typically in kitchen and garage areas.

Perhaps the safest way to do this would be to use the Dryer circuit... if there is one. It probably has the heaviest wires in the home and is usually a dedicated circuit. (although it may be 220)