Is a temporary distancing to calm things down after my parents boycotted me due to my defending someone who was wronged considered disobedience to parents?

If your distance from your parents harms them, then it is a forbidden act of disobedience. However, if it does not harm them, then it is permissible for you to minimize interaction with them to the extent necessary to calm souls, provided it is not a complete abandonment. You must not cease inquiring about them, and you are obliged to answer them when they call. It is important to note that denouncing injustice from parents is not the same as denouncing it from others.