The record doesn't show Forsberg having a higher peak. And of course his career PPG is high - he barely played after age 30.
Malkin won a Hart and a Pearson at the same time, whereas the 1 and only time Forsberg was a Hart winner, the players didn't agree and didn't think he was the best player. They chose Marcus Naslund instead.
Malkin was also a Hart finalist 2 other times whereas Forsberg was otherwise never particularly close.
During Forsberg's best career stretch (from '95 to '03) he was bested in PPG by Jagr, and equalled by Sakic while Sakic was a superior goal scorer. Forsberg was 4th in points and 37th in goals during this span.
Even if we only look at Forsberg's best season, he won the Art Ross by 2 points. His PPG lead was .1 over Joe Thornton except Thornton was a better goal scorer on a worse team. Forsberg was in a Kucherov-like position of being on a great team.
Malkin, by comparison, had a .24 PPG lead in his best season, while also scoring 50 goals. Both the media and the players thought he was the best player.
So where is the rationale that Forsberg had a higher peak?
Forsberg's peak was likely before 2003. He had three top-five scoring finishes in 1996, 1998, and 1999. He was injured much of 1997 and 2000 Remember, this was the DPE, so overall scoring was low (other than 1996). That said, his two-way peak likely came several years after this.
Jagr would be ranked above Malkin also. So would Sakic. It's not a knock on Forsberg's resume to say he was outscored by one or overshadowed by the other. Malkin was overshadowed by Crosby and Ovechkin most of his career.
Yes, Malkin has better Hart voting than Forsberg, but not significantly more. We're not comparing Forsberg to McDavid.
You're right that Forsberg didn't play much past age 30, but he outscored Malkin before they each turned 30 (1.26 PPG versus 1.18 PPG). The playoff PPG would be even higher (1.17 PPG versus 1.04 PPG). This happened during an era without a two-line pass and boring defensive systems.
That's the rationale for the rankings. Forsberg was a better scorer at his peak, in a more defensive era, and was a better two-way player.
There's certainly a great argument to be made for Malkin. You made much of it. Plus, he was a more dangerous goal scorer.