You wrote, "And that's called playing not to lose...", so my assumption was that your suggestion that the Broncos throw on the down in question, was calculated to help them win the game rather than an exercise in finding out what their rookie quarterback could do under adverse conditions.The difference here is, WTF difference did it make? It's not like the Broncos are playing for anything at this point, so why not take some chances and see what your rookie QB is made of? There's nothing macho about it. IF it ends in disaster, oh well.
Further, my assumption was that despite the fact that the Broncos had been eliminated from the playoffs, they still wanted to beat the Raiders. If the Broncos really were only interested in finding out what Tebow could do in that situation then perhaps they should have let him throw it, but if they were trying to win the game -- and I just bet they were -- then they made the correct call.