Such a statement is unbefitting of a rational Muslim, for it carries an implication no believer could possibly intend—namely, that practicing a Sunnah affirmed by all the imams, as we have detailed, would itself become a cause of splitting the Muslims and tearing their unity. Merely conceiving of that outcome is sufficient to refute the claim.
The truth for which we answer before Allah is this: there is no path to unifying the Muslims’ word and aligning their ranks except by returning to the Sunnah—especially its practical aspects—upon which the Messenger of Allah ﷺ lived his entire life, bid farewell to his community, and charged them to uphold after him.
If you would like a close-at-hand example, consider the very matter at hand: performing the prayer in the musalla.
Today, for this prayer, Muslims have dispersed into numerous separate congregations, contrary to the Sunnah as explained earlier. Should we wish to unite them in a single congregation, the only viable course is to proceed to a spacious open field that can accommodate all the worshippers, men and women alike, where they establish a musalla and perform this great act of worship—the ʿEid prayer. That is exactly what the Sunnah commands. How, then, can anyone say that implementing the Sunnah leads to disunity?!