In my very limited opinion, yes Holmgren is a forward that matches perfectly with a traditional center on offense. As always lateral quickness and perimeter defense will play a large role in being the 4 at Purdue, but those long arms will help offset some deficiencies.
If (and a HUGE if) Dickinson picks Purdue, it might actually help with Holmgren because there is no way he will have to play the 5 with Trevion, Dickinson, and Dow on the projected roster. Even without Dickinson, the depth at the 5 looks good.
The 4 also projects to be a need in 2021, especially if Wheeler leaves after his Jr year. It will be interesting to see how hard Purdue's staff goes after Holmgren this summer since 2/3 of 2020 is wrapped up.