This was a series of private conversations, causing neither harm nor offence, and there were no actual victims.
The state is therefore acting disproportionately in proscribing these mens' communication. This cannot be justified as "necessary in a democratic society" which is a requisite of any restriction on ECHR Article 10 entitlement to freedom of expression.
The convicted fellows can try that on appeal. I'm sure that won't be a waste of breath or anything