Though the Catholic Church officially states that Sacred Tradition should not and does not contradict Scripture, Protestants see much of the teaching from this Sacred Tradition as doing just that.
I think the writer of that article is very capable of understanding the Catholic answer in principle, whether he will deafen himself to it in the precise application or not. What Catholics think of that Protestant claim is very precisely what he himself thought applies to the Catholic claim:
Clearly, God's word is not contradictory. Rather, it is our understanding that is in error.
Now, God's word does contradict the refusal of Apostolic Tradition. Not just in 2 Thessalonians 2:15:
So then, brethren, astand firm and bhold to the traditions which you were taught, whether by word of mouth or by letter from us.
But also Matthew and Luke chapters 10 of each:
Matthew 10:  And whosoever shall not receive you, nor hear your words: going forth out of that house or city shake off the dust from your feet.  Amen I say to you, it shall be more tolerable for the land of Sodom and Gomorrha in the day of judgment, than for that city.
Luke 10: He that heareth you, heareth me; and he that despiseth you, despiseth me; and he that despiseth me, despiseth him that sent me.
And also the last chapter of St Matthew's Gospel, last verses with two stating the context, whom Jesus is speaking to, and three conatining the actual words:
Matthew 28: And the eleven disciples went into Galilee, unto the mountain where Jesus had appointed them.  And seeing him they adored: but some doubted.  And Jesus coming, spoke to them, saying: All power is given to me in heaven and in earth.  Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost.  Teaching them to observe all things whatsoever I have commanded you: and behold I am with you all days, even to the consummation of the world.
Which is exactly where the promise of successors to the Apostles is given, and the promise that this succession has precisely from God what Pharisees only claimed: authority to teach. However, the article does have a point:
By Jesus' own words, tradition is not to transgress or contradict the commands of God. In other words, it should be in harmony with biblical teaching and not oppose it in any way.
We do not see that he gave any Apostle any authority to command or recommend the contravention of conception within the context of marriage or any other sexual relationship. Nor do we see that he gave anyone of them the authority to set aside Genesis or Joshua in favour of Heliocentrism or Evolution.
Paris, Mairie du III
St Britius (or Brice) of Tours
*Roman Catholicism, the Bible, and Tradition, on Christian Apologetics and Research Ministry, by Matt Slick