Well, sure, but does the price include the bottle deposit?
Just kidding; if it’s at the duty-free, I’m sure it doesn’t. But that reminds me of the $40,000 bottle at a local liquor store. It’s on display and behind glass. Our little city is not known for having Scotch connoisseurs; at least, none that could afford such a bottle. I asked a friend who worked there, why they had it. She replied that they had it to draw in people who just wanted to look at such an expensive bottle. Usually, such people would buy something much less expensive, but the store still made a sale, so it was all good.
Looking at the Heathrow duty-free offerings linked above, and hearing from our American friends as to what is available in the US, I’m at a loss as to what to recommend. But I will say this: a gift of any good bottle of single-malt Scotch, no matter how available it is locally, will be welcomed by a Scotch drinker.
Of the distilleries I’ve tried from the list I’d say the Fettercain and the Craigellachie were worth consideration, with a nod to the Kilchoman and the Balvenie.
If there’s a way to get some info on your pal’s tastes (maybe via his partner?) That might give you a steer. Not just in terms of region or peated v unpeated but also age - I personally find that whiskies peak at c.15 years and by the time you’re drinking 25 y old all the character and interest had been smoothed out and you’re just tasting the wood. That’s me, but it’s not just me so worth checking if you can.
Should add, this is the perspective of a resident Scot who does a regular whisky tasting, but knows nothing about what’s available in America.
In my out of date experience, Duty Free should have some choices that are exclusive to Duty Free. A 15 or 18 year old Macallan should be welcomed by any whisky aficionado (even if not their absolute favorite).