But if 12. Bd2 Qb6 if 13. d5? Black just plays Bxa1

I am sorry but TA is talking nonsense

Be3 was played, In this game, Charles said that was played before. Plus he will end up with the B pair. Black does what he thinks is best.

I think you have to look at context here. Here is a question for you @jkarp: How many squares was that bishop influencing? Think we both can agree it was a well placed bishop on white's side. So Black, correctly, decided to get rid of a very influential piece before it became a deciding factor in the game. Before you pick and choose whose advice is right, you have to remember there is a time and place for everything. Not saying TA's advice is wrong, but here, it does not apply.

Have tried checking Nd5 for white here? Even if it gives up a pawn, it seems to be blocking the black's black bishop from doing anything significant. Either bishop has to exchange or remain idle for a long time. And the black will find it hard to protect its e5 pawn because Bc8-f5 will be met with g2-g4.