However, once each hole has wandered away into the lattice, one proton in the atom at the hole's location will be "exposed" and no longer cancelled by an electron when you have 3 electrons and 1 hole surrounding a particular nucleus with 4 protons.
However, one proton in the atom at the hole's location will be "exposed" and no longer cancelled by an electron. You have 3 electrons. You have 1 hole surrounding a particular nucleus with 4 protons. Each hole has wandered away into the lattice.