There's no such thing as an individual "giving a candidate front runner status". I don't even know what that would mean. "I hereby give Giuliani front-runner status", says person 1.. "me too!", says person 2....?
No. If Giuliani had front runner status it's because of the cumulative effect of having more supporters than the next guy. You know, supporters. Something candidates tend to have, to a greater or lesser degree. Giuliani seems to have a plurality of them. More people favor Giuliani than do, say, Sam Brownback. Big deal.
So what you're describing, instead, is the cumulative effect of a bunch of people who favored/favor Giuliani more than the next guy. Your insinuation is that a lot of those people didn't have good reasons for doing this. Your proof is that Giuliani had popularity at a time when "hadn't even formed any positions".
The thing you're overlooking/eliding (forgot?) is that Giuliani was already a nationally-known figure with a 2-decade track record that was well-known. It's not like nobody knew any single thing about Rudolph Giuliani until his Presidential campaign came out with his first official "position" on something.
So again, your whole point boils down to
a) a lot of people disagree with you about Giuliani, and
b) they can't possibly have good reasons for this. They are all stupid/ignorant, or many/most of them are, anyway.
c) They are in fact, you "infer", mindlessly basing their support completely on 9/11 in the most superficial way imaginable (i.e. because Giuliani "looked tough" and no other reason). It can't be otherwise, because after all, they disagree with you, and you're smart! So their entire reason (these people who, I remind you, are still unnamed) must be a stupid one, like Giuliani "looking tough".
Refusal to assume that those who disagree with you may have come to their views honestly/sincerely and after careful thought (i.e. (b)) is not conducive to reasoned debate. Nor are straw-men (i.e. (c)).