I disagree with the idea of that grip allowing less spin. That grip, in the hands of someone who knows what he is using it for can add lots of spin; as much spin as any grip. But that grip will cause you to contact a certain part of the ball that is more limited than some of the grips where the fingers are more on the back of the blade face.
I think Sam's point about it being easier to switch to the grip for FH or BH stroke from that may have a point. But I also know that the switch, for me happens without me even realizing it and so fast, I am not sure that would be the reason either. But, everyone is different. So, it could be the reason.
But when you mess with your grip on a serve you can create different angles for how the blade face meets the ball and therefore, you can create different spins without changing the motion of the serve. Play around with different grips and see what you get. Let yourself explore.
I know to get full backspin (almost no sidespin) on a pendulum serve, I hold completely differently from how I hold on my sidespin pendulum serves (whether side top or side back). I don't have to, but it makes it much easier to get that spin from under the ball straight forward. And the grip I use for different degrees of sidespin also changes.
Same with my reverse pendulum serves. And same with my hook serves. With the hook serves I really vary the grip a lot. With my hook serves, I have a few gips that are not too different than what Harimoto is doing in your photos, except, how I am holding my arm and my wrist is different. And on those serves I get so much spin with very little effort. So, I don't think the grip would limit the amount of spin.
But for one person it might while for another it might not. That depends on the technique used for the serve.
Play around with different grips. Explore how you can use that to change the spin on the serves.