Of course if the GOP wanted to be cartoonishly evil, they could rig the EC by getting on only a few balllot lines, but then throwing everything and the kitchen sink to win those states, so nobody gets 270, and the House can simply award the presidency to the third place candidate. Very unlikely of course, but would be very amusing.
Am I misreading this - how would that prevent the Democrat from winning if he/she had 270+ EVs?
Let's say (in a completely absurd hypothetical), Trump wins Ohio, Virginia, North Carolina and Colorado while Hilary gets the other swing states; but Mitt Romney wages a strong campaign in Utah playing up on Mormon stuff. That would leave Trump with 269, Clinton 263 and Romney 6. Then it will be thrown to the House to elect whoever the mainstream wants. That would be a ridiculous scenario, but hypothetically it is all possible.