Haani Taahir discusses and refutes this claim in his book تنزيه آي القرآن عن النسخ والنقصان, pages 91-96. He quotes a point made by M. Rasheed Ridha in his exegesis تفسير المنار, volume 3, pages 140-141, saying that the Quran has made it clear that ideas that have fermented in a person's heart are rewarded or punished, even if they never materialize. For examples, he cites these verses,
Basheer-ud-Deen Mahmood, in his exegesis, cites this verse,
I'd add that this is exactly why God has promised hell for the hypocrites, even though outwardly they do what honest Muslims do, but in their hearts they don't believe and some may be plotting against Islam. That is why God says
Therefore, Ridha concludes and Taahir agrees, that casual thoughts, even bad ones, are not punishable; only determined thoughts. As a wise man once said,
Watch your thoughts, for they become words.
Watch your words, for they become actions.
Watch your actions, for they become habits.
Watch your habits, for they become character.
Watch your character, for it becomes your destiny.
Ridha adds one more evidence the pro-abrogation scholars cited for this claim, a hadeeth reported by Ibn Hajar and narrated by Abu-Hurayra without saying he heard it from the Prophet (PBUH), in which he says, "God has let go for my community what they whisper or talk to themselves, unless they announce it or act upon it."
Ridha says it's not clear if this is Abu-Hurayra's understanding of something the Prophet (PBUH) said, and he articulated it as he understood it. Ridha says this sort of narration has happened often. It's called مرفوع (hung). I looked for this narration in the top six books of Hadeeth, but could not find it in any of them. Something similar can be found in the Musnad of Ibn Hanbal, which is not a well regarded compilation of hadeeths by most authentication scholars.
Ridha asserts that a hadeeth that contradicts the Quran should not be accepted, even if its attribution chain is authenticated.
Taahir then quotes Al-Qaasimi saying that there is no abrogation here because the context is about testimony and bearing witness. He also quotes An-Nahhaas objecting harshly to the abrogation claim saying that this is a declarative statement which cannot be abrogated and that what Ibn Abbaas, in his narration about this claim, meant by naskh is confirmation.