createing a shipping rule with a 0 dollar value will not cancel the other rules out, the shipping rules are cumulattive.
to offer free shipping, you need to add a condition to the other rules so they will not apply.
on the calculations tab, add a new calculation as:
abs([Category] == 52)?0:1
then in your shipping rules add an additional trigger:
"Subtotal for any cart column"
if the subtotal for column "applyShipping" is ">" a value of "0"