Chronologically, we’re still in the same day as Monday’s comic, when Ryan left Mike sick and for dead (or undead in this case). The passage of time isn’t really important, except to say that Mike has not yet recovered from his illness, or died of old age.
Monsters generally have a way of inspiring the public to action. Frankenstein’s creature famously had the villagers yelling for everyone to “grab your torch and pitchforks”. Various vampire hunters entered Dracula’s castle in various versions of the mythology to vanquish him, usually to great, if temporary, success. And most of the time he hasn’t even killed anyone yet. He lives in a giant spectral castle by himself. Maybe he just wants to be left alone with his sexy demon wives and servants.
But in zombie movies, people don’t usually go hunting down and destroying zombies for being evil monstrosities. The volume of zombies inspires humans to run, and then die, and then become more zombies. That’s the whole point. The story of zombie movies time and again is just about surviving to the next day in a world filled with zombies. And then a little kid looking serene says “You can’t kill the zombies. That’s impossible. Instead you must realize the truth. There are no zombies.”
And when that kid gets eaten you don’t feel bad, because what kind of world is this to grow up in anyway? And it gave the heroes time to escape. But wherever they end up, they find more zombies, because those things are everywhere. There is literally no place for them to go where life is sustainable and zombies are not. Any place that would seem sparsely populated, by zombie movie rules, will have more of the goddamned things than any other place in the world. So eventually they do the smart thing, go to that place, all die, and the credits roll. Good times.
I guess my point in the end is that, if a bunch of people sat outside a zombie’s house waiting to kill him, they’d be morons.