Well, the article said he had a spotter, so if they’re a liar, there’s more than one here.
I don’t doubt that it is difficult - but I think it is possible. The .338 Lapua is still supersonic (barely) at that range...
As for repeatability: I think it is within the realm of possibility. The rifle in question is capable of half-MOA groups or better. There’s some ferociously accurate rifles out there now. The Intl’ Benchrest Light Rifle category record set in 2007 was under 1.5” at 1000 yards with a .338 Lapua necked down to .30. For those who want to pay up for the quality, it is a heck of a time to be a rifleman...
bench rest shot at 1.5” at 1000 is a far cry from a 20” kill at 2700 yards with “duty ammo” which might shoot one MOA. Like I said - two shots concecutivly? That bullet is decending nearly verticle at that range - no wind at all in 1.54 miles?. Something just doesn’t sound right to me.
I spent a lot of bucks getting it to where it is now, but it's worth it.