That's it exactly. Hunter has enough knowledge, familiarity & inside information that there is not another person in this league that would know better.
Depending who is available, if he chooses Marner, it's because he knows how special he can be. If he chooses Strome, Hanifin or someone different, it's because he believes that person has qualities that even exceed what he knows of Marner. Because of this, I'll be happy with whoever they pick, it might not be who I would choose, but I think the Leafs & Hunter in particular will be more informed than me.
The one thing that could change their preference of picks based on their ranking is if they acquired another pick that could affect or make the 4th pick more valuable. For instance, if Hanifin & Marner/Strome were available & they saw Hanifin as the top choice, but they knew they could get Marner/Strome at #4 & a top winger that would compliment them at #6, then watch Carolina pick Hanifin at #5.
That's probably reaching a little too much, for now.