We'll wait for the D to come out and say that, if you don't mind.
For sake of argument lets say you are correct and really in communication with the D, why didn't he investigated Matt yesterday? you suspected him since day 1 and he himself suspects him. makes no sense, at all.
Now if Matt is the BG and you are wrong then the D will be whacked tonight for sure.
We have nothing to lose by keeping Matt out of jail today (having "both" BG protect the D) and letting the D investigate him or the other. You, taking an
unnecessary risk, deciding against the vast majority of C's, again makes zero sense.
I will say this to anyone who haven't figured this out yet, If ALC jail Matt everyone most vote for him today.