But would not insulting Panchali infuriate Krishna and the Panchalas even more?
If she was just kept as hostage then no one could put a finger on Kauravas. Duryodhan could continue being the emperor in peace.
Duryodhan or even Yudhishtira wasn't an emperor back then.
They were simple monarchs
And how could they keep an independent lady as hostage, that would have been highly disrespected in the society