It may very well be that the judge went overkill on the sentencing in order to get the Gov to act and reduce the sentence so they can then hammer the governor for being soft on discrimination, etc.
The guy should definitely have to pay for the damages and serve time but his sentence should not exceed that typically meted out for any other sort of vandalism against private property. Pretty sure 15 yrs exceeds the norm...
Now that I think about it, he probably got treble sentence for the hate crime aggravation. Still way harsh for a property crime. Blasephemy.