The Twitterverse has been aflame with “Homeland” fans upset about some of the plots points in Sunday’s show — Spoiler Alert! — particularly the one about terrorist Abu Nazir hacking into Vice President Walden’s pacemaker to kill him, with the help of Congressman Brody. Critics are claiming that’s impossible, but they should have read this 2008 New York Times story, which is obviously where the “Homeland” writers got the idea.