How do the Spirit Guardians and Sanctuary spells interact?

A player in my group asked the DM:

  1. What if Cleric 1 was to cast spirit guardians and go for the heart of battle
  2. Then Cleric 2 cast sanctuary on him
  3. Then Cleric 1 just sits there not actively attacking, probably taking the Dodge action while keeping concentration on his spell.

This makes it OP because he would be sitting there dishing out massive damage, while enemies would have to make a DC 15 Wisdom saving throw to hit him, and if they actually succeed they would have to hit with disadvantage due to the Dodge action.

The crucial point lies in the wording of sanctuary:

If the warded creature makes an attack or casts a spell that affects an enemy creature, this spell ends.

Cleric 1 cast spirit guardians before sanctuary came into effect, so he will not attack or cast something for the time being; he just sits there.
But he is also keeping concentration on a spell that harms others.
What do you think? Does the sanctuary spell end or not?