re: A proton diameter = 1 millionth of a nanometer
A proton diameter = 10^(-15) meters -- depending on the literature source.
At relativistic speeds the proton will be contracted in the direction of travel, providing much more time to nudge it sideways by a proton-diameter so that it could pass through the gaps in the porous shield and be transformed into a slow massive W-boson. So basically I have no idea if it would be possible or not.
The ultimate shield would be one that converts all incoming debris and radiation entirely into neutrinos which would pass harmlessly through and aft of the starship. This would require a godlike grasp of nuclear physics that mankind obviously doesn't possess.
But now that I've put forward the idea, who knows what the future will bring.... :-)