Actually, an election would get thrown into the House if no one got 270 electoral votes, which could happen even in the absence of a third candidate receiving EVs if (i) it’s a 269-269 tie or (ii)someone wins 270-268 but one of the presumptive winner’s electors abstains from voting (which is precisely what one of Gore’s electors from DC did in 2000, which is why Bush won 271-266 with 1 abstention).
And besides, while it is correct that no third-party candidate has earned EVs since 1968, there have been several instances of “faithless electors” voting for someone else (a Nixon elector from NC voting for Libertarian John Hospers in 1972, a Ford elector from WA voting for Ronald Reagan in 1976, a Dukakis elector from WV voting for Dukakis’s runningmate Lloyd Bentsen in 1988, and a Kerry elector from MN voting for Kerry runningmate John Edwards in 2004). Plus, just because no third-party candidate has carried a state (or a CD in the states that allocate EVs by CD) in the past 48 years does not mean that it will never happen again.
I didn’t say it was impossible for the election to go to the House, just that it is not likely to happen. The last time the election got thrown to the House was in 1825.
Also, the scenario that the article is concerned with is not the unlikely event that the election is decided by the House, but the further unlikely event that one of the top three candidates drops dead before the House decides.