My company operates the CFM equipped A320s, and here is the guidance from the NOR.
"During ground operation, when in icing conditions for more than 30 min, the following procedure should be applied for ice shedding:
If ground surface conditions and the environment permit, the flight crew should accelerate the engines to approximately 70 % of N1 for 30 s at intervals not greater than 30 min. In addition, this engine acceleration should also be performed just before take-off, with particular attention to engine parameters to ensure normal engine operation."
I can see there is cause for confusion here, but it is interpreted as:
If you are in icing conditions for MORE THAN 30 mins, you need to do a run-up every 30 mins, as well as immediately before takeoff.
If your taxi time is LESS THAN 30 mins, no runup is required.
The note "In addition, this engine acceleration should also be performed just before take-off..." is still under the header of "During ground operation, when in icing conditions for more than 30 min" so it only applies if you are more than 30 mins taxi out time.
Under 30 mins, no runup required.
Of course management could have come up with more restrictive guidelines based on their operational experience, or they could have misinterpreted the guidance from the Airbus FCOMs, in this admittedly poorly written paragraph.