Tell him to go to terminal one if he has the time.
World of Whiskies is there (ignore the duty free shops, which have WoW sections - they have their own shop down near the bottom of the concourse past the pub).
They keep their stock updated here -
http://www.worldofwhiskies.com/You're not going to find anything especially good in terms of Irish, though. They have barely the standard ranges. No Bush 21, no Jameson Gold, very little Cooley when I was last there. But they do have some great Scotch options.
When I was through earlier this month, I picked up a Glenfarclas 21 yo for £41, and a litre bottle of Bunnahabhain Cruach Mhona for around £60. And I picked up a 36 year old sherried Strathisla which was very reasonably priced. There are always specials in the shop and it's worth his asking the knowledgeable staff, especially the little bald man, as he spent decades in the whisky industry.
They usually have some nice single cask independent offerings at a decent price too. And there'll likely be some travel retail exclusives.
And remind him to actually inform them their Irish whiskey selection is abysmal. They know this, but the more customers who tell them, the more inclined they'll be to change.
