First of All™, your whole post is based on a false ultimatum: the Hall of Fame is not a zero-sum game. Horford's eligibility into the Hall has nothing to do with Webber's, or vice versa. It's not like Horford getting in would mean that Webber couldn't; hell, he might already be in by the time Horford is even eligible.
Second of all, Horford has two NCAA National Championships to help his case (I don't know why people always forget that it's the Basketball Hall of Fame, not the NBA Hall of Fame), plus he has a reputation as "Winner Guy," as well as a much better reputation among the voters.
I said it when Webber didn't make the cut the first time, I said it again when he didn't make it the second time, and I'm going to keep saying it: I don't see Webber getting in, until and unless he makes good with Michigan, and buries the hatchet with the rest of the Fab Five.