That's a great point. Also, if you watch the 40 run of Taylor Mays when he unofficially ran his 4.24, he has an unconventional start yet it was the fastest at that years combine. I say if someone tried to change it, it would have been a slower time. BTW, his coach for that combine was Chris Carlisle, a believer in perfecting and not changing.
Coach it's funny you'd reference Taylor Mays, a guy that's so athletically gifted many saw him as a no brainer first round talent, and many more were shocked when his college coach Pete Carroll passed on him and drafted another safety instead.
Despite being a second round pick, with protypical size and speed and a NFL bloodline, Mays can't stay on a NFL team despite the league being in desperate need of safety's with his skill set.
Mays thought there was a conspiracy when he didn't go in the first round, he thought former coaches planted rumors about him, that turned out not to be true. The facts are he isn't good enough to be a consistent NFL player.
In the regards to Tebow I think this is the case as well. Teams look at players as commodities that are either appreciating or depreciating. As a player ages if he hasn't developed in the desired way teams move onto younger players, that doesn't mean their career is over though they just have to mature in different leagues.
There's an old saying among teams that says you are what the game tape says you are. In Tims case he's not a viable starting or backup option. Most teams aren't carrying a 3rd string qb, and if they do they stash them on the practice squad. Because he's acquired 3 years experience on actual teams Tebow is ineligible to be a practice squad player.
All that said I'm sure teams don't like the media attention he gets as a backup, and that may keep him off of teams radars, but if he was a viable option to help they'd put up with it. I don't think there'd be a conspiracy to keep him off a team, as that would also be some type of collusion.