Excellent (agreed!) points, and I've struggled with these same concerns about FTT as he puts himself with Rory & Travis, and using drugs, and though he said he passed out, and he can't remember some things, how convenient is that for him. Well, maybe he conveniently doesn't remember being at the Treehouse and committing the crime, too?
He is a liar, but is the jury able to convict according to law? There is direct (eye witness account) evidence, hence, Johnson's testimony, and there is circumstantial evidence, which establishes that FTT is connected to the crime, he put himself at the Treehouse on that fateful day.
In addition, I've wondered if FTT had a beef with Matt over the renting issue as well?
All is jmo