It sort of depends how things turn it in terms of the other moves they make. Right now, according to the Seattle media, they're trying to sign and trade Rashard Lewis by trading Battier and some other stuff. Assuming that happens, then we're looking for a stopgap measure for the power forward spot (because there really aren't very many on the free agent market) and I guess Webber fits that bill.
If the Lewis deal doesn't go down (and to be honest I'll assume it doesn't), then I'm assuming they're going to search for other guys first at the PF spot. They've also been looking at dealing for Chris Wilcox but I'm leery of him after the whole Stromile Swift debacle. But Webber's at the bottom of the list primarily because they want an athletic guy who can rebound and play defense, neither of which is Webber's specialty anymore.
After all, we have one washed up member of the fab five, so I'm not sure another one is really necessary. I think Antonio McDyess would be the more likely target for the Rockets. It also doesn't hurt that McDyess lives in Houston.