Most pundits said that Philip Rivers' throwing motion would have to be "retrained" in order to succeed in the NFL. Things seems to have worked out quite nicely for him -- awkward throwing motion and all. If Tebow is accurate (and I don't keep up with his stats), I think it would be foolish to try to fix something that ain't broke.
The question on Rivers was his throwing motion not the quickness of his release. Tebow's release time is a much much greater concern than throwing motion. I think there might be a team to take him on as a project but he definitely won't keep that same release time and succeed in the NFL.