It’s not the damage to the book necessarily, but the complete lack of respect and intention to cause anger.
It would kind of be like burning a Constitution and American Flag on Independence Day in front of the Capitol or maybe Washington Monument. Or lighting a cross on fire in front of the Lincoln memorial on Juneteenth or MLK Jr. Day. Or setting up Swastikas in front of synagogues during Passover.
It’s essentially intentionally spreading hate. Now, if you burn a Torah, Qu’ran, and Bible as an anti-religion demonstration on some random day of the year, that’s a completely different thing. But doing such a demonstration on a religion’s holiest of days in front of that religion’s places of worship is a very different matter.