I can sum this up very nicely:
Rex is a Defensive Coordinator who is also Head Coach. Something to keep in mind (always.)
In his mind, (even though Lindley is absolutely horrendous) his Defense was effectively pitching a shutout.
Rex will not tolerate his defense losing games that they are effectively winning.
Additionally, Tebow was not dressed.
Essentially, if you really want to analyze this, you can surmise that Woody is meddling a lot more than any of us think.
Perhaps Sanchez has been glued to being the starter because
A) Woody loves him.
B) Rex was not going to pull Sanchez for Tebow and uncork an entirely new set of worms.
Or perhaps Rex did legitimately think that a QB who barely completes half of what he throws can win him a Super Bowl.
My personal belief is that Rex realized the team had a cloud hanging over its head with Sanchez out there and actually, for once, coached for his job instead of catering to the wishes of the owner.