At one point in the wilderness, people went to Moshe, and lamented that they were impure at the time the Korban Pesach was offered, and wanted inclusion in the mitzvah. Their feedback was legitimate, and the law of Pesach Sheni was revealed.
Yet Korach too sought more inclusion – that everyone ought to have access to the holy service, not just the Kohanim. His demise was swift.
What is the difference between what they wanted if their complaint was essentially the same?
There is a concept that all negative characteristics have a positive application – for example, it is permitted to be jealous of a tzaddik or great scholar. Such jealousy can foster aspirations, that if realised, transform a person. This operates on the stepping-stone principle that מתוך שלו לשמה, בה לשמה – misdirected thought can nonetheless develop into legitimate action and intent.
However, there is a caveat to this rule. Not all misguided actions are reparable in the long term – one type of action will never become legitimate – argument. The Mishna in Pirkei Avos 5:17 says כל מחלוקת שהיא לשם שמים, סופה להתקים. ושאינה לשם שמים, אין סופה להתקים.
איזו היא מחלוקת שהיא לשם שמים? זו מחלוקת הלל ושמאי. ושאינה לשם שמים? זו מחלוקת קרח וכל עדתו – Any argument for the sake of Heaven, will endure in the end. One that is not for sake of Heaven, will not endure. What is the paradigm of an argument for the sake of heaven? Hillel and Shamai. What is the paradigm of an argument not the sake of Heaven? Korach and his congregation.
Is it simply that an argument in Torah will endure, and that politics will not?
R’ Yaakov Minkus explains that there is more to it than that. Adding the mitzvah of Pesach Sheni was not a problem – the Torah was not closed canon yet. Korach however, was looking to cause issues and rifts.
Hillel and Shamai were looking to build halachos, and build a system to live by. From one’s point of view, we understand the other better. We need both to build and consolidate. A losing argument is included in the Gemara because it is a valid view that aids in understanding the issue.
Not so with Korach. His arguments were not constructive at all. His claims and goals were literally baseless and without foundation – note how the ground on which he stood collapsed beneath him – he was not fighting for anything real. The same is certainly not true of the Pesach Sheni crowd – therein lies the difference.
The Mishna says as much too. The paradigm of an argument not for the sake of heaven is “Korach and his congregation.”. If the parallel to Hillel And Shamai were correct, it ought to have said “Korach and Moshe”. Korach wasn’t really fighting anyone at all – it was just about causing a stir and breaking down the system that existed.
This is what Rashi and the Targum mean – ויקח קרח – “And Korach took” – What did he take? Himself, to one side.
It was never about Moshe. It was about causing a stir. The Pesach Sheni people wanted to be close to God – the parallel to Korach’s falls away swiftly.