What if Taln "CHOSE"?
I take a different approach to "Taln didn't break"
We know the cycle of desolations was not particularly good for humans or singers in the end. While Taln's sacrifice was great for society, it did not heal the wounds of Roshar, mearly acted as a potent band aid for the problems. The parhmen were slaves for thousands of years.
What if he did not break, but CHOSE to let the fused return. Maybe he gained new insight or knowledge that made him realize the only way to fix the world was to resolve its problems.
I prefer this theory because it does not cheapen the end of Taln's time in Braize.