It doesn't matter if they're "in visual range". You knew they were trying to detain you, so you decided to alert your whole faction by saying "We're being detained at the ICC" at least 3 times. You had ample time to stop, and chose not to.
The fact that the PK guidelines don't specifically mention using radios while under FearRP doesn't matter; you're informing your faction members of information which could lead to severe legal repercussions against those who were detaining you.
I will wait for @Aurelius of Phoenix and @dawgto reply, as well as for you to provide any further insight, before I make a decision on this.