When you talk about slow that is Nam's skating. Nathan's speed has noticeably increased in the last couple years as he got bigger and more powerful. He's not speedy but i wouldn't call him slow and at his age he can make big improvements in a matter of months.
Nathan was slow in Barcelona 2015 and he was slow in Marseille 2016. I wonder how many have actually watched him live over multiple seasons, tbh.
He can make big improvements, I don't see any reason to judge him over potential improvements that maybe we'll never see, tho.
I guess it's the same about his GOEs judging, tho. Potentially he has the skills to hit them all, so let's give him +2 and +3 when he hits maybe half a bullet.