The first verses of Matthew 23:1-3 are not directed to the Pharisees, but to Jesus' followers, and are not mocking anyone at all -- they are dead serious.
The core of the passage is that Jesus is instructing his followers to obey the pharisees in EVERYTHING they teach (which is going to include Oral Torah as well as Torah, obviously). He prefaces this remark with the reason for it: they sit in Moses seat. This is because the Pharisees are the legitimate successors of the judges/elders before them, whom Moses appointed, just as the Rabbis will be after them, meaning they have the authority to teach as well as interpret Jewish law as per Deut 17;8-13.
Jesus also follows it up with a kind of, "and don't forget" LOL. What comes out of their mouths is one thing and what they do is another -- it's only what comes out of their mouths that has teaching authority, so don't pay any attention to what they do.
NOTICE THAT JESUS DOES NOT REQUIRE THE PHARISEES TO BE GOOD MORAL PEOPLE IN ORDER TO BE AUTHORITATIVE TEACHERS AND INTERPRETERS OF THE TORAH.
A requirement of Moses.
Ex 18:21 Moreover thou shalt provide out of all the people able men, such as fear God, men of truth, hating covetousness; and place such over them, to be rulers of thousands, and rulers of hundreds, rulers of fifties, and rulers of tens:
The Pharisees were called snakes and vipers by john the Baptist. Would they even qualify for a lower court?
Mt 16:6 Then Jesus said unto them, Take heed and beware of the leaven of the Pharisees and of the Sadducees.
Mt 16:11 How is it that ye do not understand that I spake it not to you concerning bread, that ye should beware of the leaven of the Pharisees and of the Sadducees?
Mt 16:12 Then understood they how that he bade them not beware of the leaven of bread, but of
the doctrine of the Pharisees and of the Sadducees.
Mr 8:15 And he charged them, saying, Take heed, beware of
the leaven of the Pharisees, and of the leaven of Herod.
mt 15:9 But in vain they do worship me,
teaching for doctrines the commandments of men.
But as the seat of Moses included not mere sectarian bent, but the high priest by duty of office before the Lord....That did not matter their Moral Character.
As his ( high priest) sentence was .........
jn 11:49 And one of them, named Caiaphas,
being the high priest that same year, said unto them,
Ye know nothing at all,
50
Nor consider that it is expedient for us, that
one man should die for the people, and that the whole nation perish not.
51 And this
spake he not of himself: but being high priest that year, he prophesied that Jesus should die for that nation;
52 And not for that nation only, but that also he should gather together in one the children of God that were scattered abroad.