I can't speak to the validity of that rumor at all. Eklund wouldn't be my pick at #1, but I could definitely see where it makes some sense for Buffalo.
Development has been an issue. Even can't-miss prospects like Reinhart and Dahlin have stuttered at times in development (although I'm a believer in both players), and they've really struggled to integrated later round picks outside of Olofsson. Eklund strikes me as pretty bright and pretty well-rounded. I think if you leave him in Djurgardens another year and he stays healthy and performs well, he's probably in pretty good shape. Not every team can afford to swing for the fences with these picks, and I could see where the "safety" of a pick like Eklund could appeal to Buffalo.
Further, I think Eklund is a versatile enough prospect where there aren't really concerns about fit in a system. He's bright in controlled 5v5 play, he's been good in transition this year, he's a pretty tenacious defender. For a team like Buffalo who has mowed through like half of the coaches and GMs in the league, I can see where that versatility has a lot of value. If some of the Eichel/Reinhart/Risto rumors are true, there will likely be pretty significant roster turnover in the coming years. In that case, a versatile player like Eklund is probably a reasonably safe bet to make it through the storm.
I'm not a big believer in Kevyn Adams as Sabres GM. But with so much personnel turnover going on, I can see where Eklund makes a lot of sense. I think the same is true for players like Power and Beniers to an extent, but it's a close race this year and the Sabres taking Eklund at #1 would be a pretty justifiable move in my eyes.