Question: Eligibility for Increased Exemption for Redundancy Lump Sump

Here's the scenario for one of my friends who is being made redundant and we are debating whether he is eligible for increased exemption:

1. He was made redundant from his previous job in 2014. However, the lump sum he received was below the basic 10,1160.

2. He has not been made redundant or received any other lump sums in the previous ten years aside from the above.

3. He is not being made (involuntarily) redundant from his current word and the lump sum offered to him is in excess of 20K.

The questions is: Is he eligible for the increased exemption considering that he did not avail of that in his previous redundancy lump sum? Or is the fact the he received any sort of lump sum make him ineligible for increased exemption?

My understanding is that since he has never made a claim for increased exemption he is entitled to it. This is based on revenue IT21 leaflet which says:

you have not made any claims in respect of a lump sum received in the previous ten tax years.

But it only says "claim" in the above. Does that mean any claim, or claim for increased exemption specifically.

according to a guide on Mercer:

You may be able to increase your exemption by €10,000 to €20,160 plus €765 for each complete year of service provided that you have not made a claim for the increased exemption amount in the previous ten tax years.

But Citizen Information says:

f you haven't received a tax-free lump sum in the last 10 years and you are not getting a lump sum pension payment now or in the future

Which one is the case? Is there anywhere that he can check for specific wording of legislation on this?

Any advice would be greatly appreciated.

Regards
Ashkan